Science 10 physics

Who was Robert Steele?

-patented an engine fuelled by gas from tar and oil

What is wind energy?

-result of heating of the earth by the sun, which cause convection currents of air or wind. -energy of the movement of air is used to turn turbines. The kinetic energy of the turbines is then converted into other forms such as electrical energy

What are the three conditions for work to be done on an object?

1. There must be movement 2.There must be force 3.The force and the distance the object travels must be in the same direction.

What are the two scenarios that are positive acceleration?

1. both the change in the magnitude and the direction of the velocity are positive. 2.both the change in the magnitude and the direction of the velocity are negative. (slowing down in the negative direction)

What are non-solar energy sources?

1. nuclear energy that result from a nuclear reaction. Can be fission that occur in a CANDU reactor or fusion in sun 2.Geothermal energy- thermal energy from the earth's interior. Superheated water rushes to earth's surface through geysers and hot springs and can be used to generate electricity. -found in place with volcanic activity 3.tidal energy- the movement of ocean water creating tides. The kinetic energy of this can be converted to other forms.

Who contributed to the first law of thermodynamics?

A Scottish physician named Joseph Black in 1750 -observed that when a cold object is placed in a cup of water, and then removed, the object becomes much warmer -suggested that heat was an invisible fluid

What is force?

A force is a push or a pull that acts upon an object as a results of its interaction with another object. Forces result from interactions!

How does energy transfer take place on a roller coaster?

A rollercoaster car converts GPE to KE when it rolls down the track The rollercoaster car gains GPE as it travels to the top. Once over the top, the car gains speed as GPE is transferred to KE. As it travels to the top of another loop, KE is transferred to GPE. Note that not all the energy is transferred to or from GPE - some is transferred to the surroundings as heat and sound.

How does a solar cell work?

A solar cell is usually composed of two layers of silicon, one with phosphorus added and one with boron added (Figure B2.20). Normally, electrons are bound up in the silicon crystals in these layers. However, when sunlight hits the silicon layers, it provides energy for some of the electrons to break free of the crystals and move freely. The silicon layer with added phosphorus becomes negatively charged. The second silicon layer with added boron becomes positively charged. The positive and negative layers act in the same way as the positive and negative terminals of a battery, and an electric current flows. The current is then collected by the electrical contact layers shown in Figure B2.20. The electricity can be used directly or stored in a conventional battery for later use. This energy conversion system can be applied to systems as large as the International Space Station or as small as a solar-powered calculator.

What is uniform motion?

A term used to describe an object that is travelling at a constant rate of motion in a straight line.

What is average speed?

An uniform motion that involves travelling a distance in a specified time. Average speed= distance travelled/time elapsed V= delta distance/ delta time *An object with no movement at all has a zero speed.* The average speed during an entire motion can be thought of as the average of all speedometer readings. If the speedometer readings could be collected at 1-second intervals (or 0.1-second intervals or ... ) and then averaged together, the average speed could be determined. Now that would be a lot of work. And fortunately, there is a shortcut. Read on.

What did Thomas Young do?

Around 1807, he lined ME to Leibniz's theory of kinetic and potential energy in moving objects. While Leibniz though an object had either kinetic or potential energy, Young correctly suggested that ME combined both KE and PE. He also thought that ME was related to the work a system do. This led to the current definition of energy, the capacity to do work

What did James Prescott Joule do?

In 1840s, he properly substituted the term "energy" for vis viva. H argued that heat is just another form of energy.

is nuclear renewable or non-renewable energy?

It is non-renewable because these are limited an irreplaceable.

Position

Location described in relation to a reference point

What is useful energy output?

The desired energy needed to do the work

What is chemical potential energy?

The energy found in chemicals, a form of potential energy as well. This energy is stored in the bonds of chemical compounds. When a chemical change takes place, the positions of electric charges are altered and energy is released. Any substance that can be used to do work through a chemical reaction has potential energy. ex) the PE of fossil fuels such as gasoline is only released when the gasoline undergoes a chemical combustion reaction.

Ben Tooclose is being chased through the woods by a bull moose that he was attempting to photograph. The enormous mass of the bull moose is extremely intimidating. Yet, if Ben makes a zigzag pattern through the woods, he will be able to use the large mass of the moose to his own advantage. Explain this in terms of inertia and Newton's first law of motion.

The large mass of the bull moose means that the bull moose has a large inertia. Thus, Ben can more easily change his own state of motion (make quick changes in direction) while the moose has extreme difficulty changing its state of motion. Physics for better living!

Motion

The motion of an object occurs when an imaginary line joining the object to the reference point changes in length or direction or both.

What is the net force?

The net force is the vector sum of all the forces that act upon an object. That is to say, the net force is the sum of all the forces, taking into account the fact that a force is a vector and two forces of equal magnitude and opposite direction will cancel each other out.

What is the work output?

The object gains energy as a result of this work done on the object. This is called energy output or work output.

What is the useful work output?

The work the machine is supposed to do

Who invented the first steam-powered pump and discuss the drawbacks.

Thomas Savery. It was used to pump water out of mines. The drawback is that it could not lift the water very high and required steam to be in a higher pressure.

What are the two main forces that act upon falling objects?

Weight and air resistance

How do you calculates the weight of an object?

Weight= mass x gravitational acceleration The acceleration due to gravity represents the strength of Earth's gravitational field. (weight is basically the same as force, as you can see by the similarities of these two formulas)

What is the difference between work and heat?

Work involves the movement of matter from one location to another, whereas heat is a transfer of thermal energy from one location to another. Both heat and work can affect systems.

Supposing you were in space in a weightless environment, would it require a force to set an object in motion?

YES!!! Weight DOES NOT equal mass. Even in space objects have mass. And if they have mass, they have inertia. That is, an object in space resists changes in its state of motion. A force must be applied to set a stationary object in motion. Newton's laws rule - everywhere!

Is a change in temperature also considered as an evidence of energy transfer?

Yes, for a pot of water on the stove, energy is being transferred from the hot stove to the cooler pot and water. The pot and water are gaining heat. Heat is the transfer of kinetic energy of the particles in one substance to another; in this case from the element to the pot and water.

What energy transfer happens in many musical instruments?

You said: Kinetic to sound Correct Many musical instruments convert kinetic energy to sound energy. This happens in all string and wind instruments.

What is efficiency?

a measurement of how effectively a machine converts energy input into useful energy output. efficiency= useful work output/ total work input

What is fossil fuels?

ex) oil, natural gas and coal -formed from plants and animals that lived billion of years ago

What is the energy input?

initial energy source

What are renewable energy sources?

ones that are continually and infinitely available ex) solar, wind, water, geothermal, tidal, biomass

What is gravity force?

(also known as Weight) Fgrav -Weight is basically force The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. By definition, this is the weight of the object. All objects upon earth experience a force of gravity that is directed "downward" towards the center of the earth. The force of gravity on earth is always equal to the weight of the object as found by the equation: Fgrav = m * g where g = 9.8 N/kg (on Earth) and m = mass (in kg) A 1.0-kg mass is suspended from a spring scale in an effort to determine its weight. The scale reads just short of 10.0 N - close enough to call it 9.8 N. Mass refers to how much stuff is present in the object. Weight refers to the force with which gravity pulls upon the object.

What is electrical energy?

energy in moving charges or static electric charges -the work done by moving charges

What is sound energy?

energy released by vibrating objects

Why does the elephant fall faster than the feather when dropping off a building, considering air resistance.

he elephant and the feather are each being pulled downward due to the force of gravity. When initially dropped, this force of gravity is an unbalanced force. Thus, both elephant and feather begin to accelerate (i.e., gain speed). As the elephant and the feather begin to gain speed, they encounter the upward force of air resistance. Air resistance is the result of an object plowing through a layer of air and colliding with air molecules. The more air molecules which an object collides with, the greater the air resistance force. Subsequently, the amount of air resistance is dependent upon the speed of the falling object and the surface area of the falling object. Based on surface area alone, it is safe to assume that (for the same speed) the elephant would encounter more air resistance than the feather. But why then does the elephant, which encounters more air resistance than the feather, fall faster? After all doesn't air resistance act to slow an object down? Wouldn't the object with greater air resistance fall slower? Answering these questions demands an understanding of Newton's first and second law and the concept of terminal velocity. According to Newton's laws, an object will accelerate if the forces acting upon it are unbalanced; and further, the amount of acceleration is directly proportional to the amount of net force (unbalanced force) acting upon it. Falling objects initially accelerate (gain speed) because there is no force big enough to balance the downward force of gravity. Yet as an object gains speed, it encounters an increasing amount of upward air resistance force. In fact, objects will continue to accelerate (gain speed) until the air resistance force increases to a large enough value to balance the downward force of gravity. Since the elephant has more mass, it weighs more and experiences a greater downward force of gravity. The elephant will have to accelerate (gain speed) for a longer period of time before there is sufficient upward air resistance to balance the large downward force of gravity. Once the upward force of air resistance upon an object is large enough to balance the downward force of gravity, the object is said to have reached a terminal velocity. The terminal velocity is the final velocity of the object; the object will continue to fall to the ground with this terminal velocity. In the case of the elephant and the feather, the elephant has a much greater terminal velocity than the feather. As mentioned above, the elephant would have to accelerate for a longer period of time. The elephant requires a greater speed to accumulate sufficient upward air resistance force to balance the downward force of gravity. In fact, the elephant never does reach a terminal velocity; the animation above shows that there is still an acceleration on the elephant the moment before striking the ground. Observe from the above diagrams and the above animation that the feather quickly reaches a balance of forces and thus a zero acceleration (i.e., terminal velocity). On the other hand, the elephant never does reach a terminal velocity during its fall; the forces never do become completely balanced and so there is still an acceleration. If given enough time, perhaps the elephant would finally accelerate to high enough speeds to encounter a large enough upward air resistance force in order to achieve a terminal velocity. If it did reach a terminal velocity, then that velocity would be extremely large - much larger than the terminal velocity of the feather. So in conclusion, the elephant falls faster than the feather because it never reaches a terminal velocity; it continues to accelerate as it falls (accumulating more and more air resistance), approaching a terminal velocity yet never reaching it. On the other hand, the feather quickly reaches a terminal velocity. Not requiring much air resistance before it ceases its acceleration, the feather obtains the state of terminal velocity in an early stage of its fall. The small terminal velocity of the feather means that the remainder of its fall will occur with a small terminal velocity. As learned above, the amount of air resistance depends upon the speed of the object. A falling object will continue to accelerate to higher speeds until they encounter an amount of air resistance that is equal to their weight. Since the 150-kg skydiver weighs more (experiences a greater force of gravity), it will accelerate to higher speeds before reaching a terminal velocity. Thus, more massive objects fall faster than less massive objects because they are acted upon by a larger force of gravity; for this reason, they accelerate to higher speeds until the air resistance force equals the gravity force.

How can you observe kinetic energy and gravitational potential energy in nature?

1. Flowing water, wind, or any object in motion could be made to do work because of its motion, and thus has kinetic energy. 2.An object raised above Earth's surface has the potential to do work because of its position, and thus has gravitational potential energy.

What are some evidence of energy conversions?

1.Motion-KE 2.Climbing stairs of a diving tower-GPE 3.Change in shape- EPE A drawn bow has gained EPE as the archer pulls the bow string back, changing its shape. When she releases the bow, it will change its shape again as the EPE changes to KE of the released arrow. A stretched elastic band or a pole vaulter's pole mid jump has gained EPE.

How does a coal-burning power station work?

A coal-burning power station also uses many energy conversions to generate electricity (Figure B2.18). Coal is placed in the combustion chamber, A, where it burns at a very high temperature. The chemical potential energy in the coal is converted into heat. This heat is then used to change the water in the boiler, B, into steam. The steam is under pressure and is injected into the turbines, C, causing the turbines to rotate. The thermal energy and kinetic energy of the moving steam is converted into kinetic energy as the turbines rotate. The turbines use the kinetic energy to turn a coil of wire in a magnetic field in the generator, D. The kinetic energy is converted into electrical energy

What is energy?

If a body has energy, then the body can do work by transferring the energy to another object. This leads to the definition of energy. Energy is the ability to do work.

Conversion and Conservation of Energy in aPendulum

The pendulum is an excellent example of the law of conservation of energy.When the pendulum is initially lifted a certain height above the table, work is done against the opposing force of gravity. The energy expended to do the work is stored in the pendulum as gravitational potential energy. When the pendulum is released and begins its swing, gravitational potential energy is converted into kinetic energy, and the pendulum speeds up. At the midpoint of the arc, the pendulum is moving at its maximum speed, and all the potential energy has been converted into kinetic energy. At this point, the kinetic energy of the pendulum is exactly equal to the initial amount of potential energy. As the pendulum begins to rise toward its maximum position on the other side of its arc, the pendulum slows down, and kinetic energy is converted back to potential energy. At the highest position on the other side,the pendulum stops and has no more kinetic energy. Its potential energy equals the amount of potential energy it had at the beginning because it rises to exactly the same height. Energy is conserved!

How can energy of a system be increased?

Either heat can be added to a system from the surrounding, or work can be done on a system by its surroundings. Work done on the system by the surroundings is considered positive work because the energy of the system increases.

How can the energy of a system be decreased?

Either heat can flow out of a system to its surroundings or work done by a system on its surroundings, this is considered negative work because the energy of the system will decrease.

How does energy transfer when you apply a force?

The person applying the force to the ball transfers energy to the ball. If the unbalanced force, such as friction between the table and the ball, is applied in the direction opposite to the direction of the ball's motion, the ball will slow down. Without such a resistive force, the ball would tend to keep moving.

What is exactly velocity?

Velocity is a vector quantity that refers to "the rate at which an object changes its position." Imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. While this might result in a frenzy of activity, it would result in a zero velocity. Because the person always returns to the original position, the motion would never result in a change in position. Since velocity is defined as the rate at which the position changes, this motion results in zero velocity. If a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. Every step must go into moving that person further from where he or she started. For certain, the person should never change directions and begin to return to the starting position.

How can we analyze motion?

We can analyze motion only if we compare the object's position to another point. This point is called the reference point.

What is nuclear energy?

energy stored in the nuclei of atoms -potential energy stored in the nucleus of an atom. When the nucleus of an atom is split (nuclear fission) or when the nuclei of two atoms combine (nuclear fusion), this energy is released.

What is biomass?

-any form of organic matter, since the store solar energy from the sun through photosynthesis, these can be combusted to release chemical potential energy

Who was James Watt?

-designed a new, more efficient steam engine. -reduced the amount of heat required to operate the steam engine drawback:- size is too big, very inefficient at converting heat to useful energy

What did Sadi Carnot do?

-performed experiments in an attempt to transform hear into ME, but realized that the transformation of heat into ME could only occur when thermal energy flow from a hot to a cool object

What is a system?

A set of interconnected parts. In studies of work and energy transfers, the system is the object or objects involved in the transfers. Everything else is considered the surroundings or the environment.

Define the types of systems there are.

An open system is one that exchanges both matter and energy with its surroundings. For example, suppose Earth is a system and the universe is its surroundings. Earth is an open system, since it can exchange both energy and matter with its surroundings. • A closed system is one that cannot exchange matter but can exchange energy with its surroundings. For example, a closed can of soup is a closed system because matter cannot move into or out of it, but energy can move into the can. • Anisolated system is one that cannot exchange either matter or energy with its surroundings.

When is potential energy only useful?

As you know, PE is energy that is stored and has the potential to do work. So, PE is only useful when it's converted into some other form of energy. -the EPE only becomes useful when it's converted into the KE of the moving cork. This is true of all types of PE. The PE of a battery only becomes useful when it's converted into electrical energy. The GPE of a diver on a diving tower only becomes useful once the diver starts to dive.

What does the first law of thermodynamics states?

Basically just a restatement of the law of conservation of energy, except one of the forms of energy involve is heat. This law states that the total energy, including heat, in a system and its surroundings remain constant. Whenever heat is added to a system, it transforms into an equal amount of some other form of energy. -the energy that is supplied to a system must equal all the energy that is gained by the system. ex) the energy your body receives from food must equal to the energy of all the useful work done, plus all the wasted energy, including heat, mechanical energy of the moving parts of your bod. since heat can increase the energy, meaning that it can increase the work done. -when heat is added to a system, some of this energy will be used to increase the energy of a system, which will increase the temperature and so it is used to move parts or to do work on the system. heat added to system= mechanical energy+heat

How do you find the work input?

By calculating the area under the line of best fit.

Who experimented with a more "successful" reciprocating pump and discuss the drawbacks of it

Christian Huygens, he experimented with a gunpowder engine, in which gases generated by an explosion inside the engine drove a piston forward into a cylinder. It was not developed because of the hazards of explosion and there was no powerful internal mechanism to pull the piston back so that the engine could work forever.

Who designed the first steam engine and discuss the drawbacks.

Denis Papin in 1690. It uses heat to create steam to do work. However, he did pursue the development because he had difficulty making the large drum in which the water was to beheated

How do you calculate force?

Force= mass x acceleration

Who was Otto von Guericke?

He demonstrated the force of vacuum by fitting 2 hollow hemispheres together and created a vacuum inside by extracting the air through a valve. Two teams of eight horses pulling in opposite directions could not pull the hemisphere apart. -water increases its volume by 1300 times when heated to form a steam.

Who was Eugene Langen?

He invented the first internal combustion engine- energy was released by burning fuel, ignited by an electrical spark. drawback: still very inefficient and could not produce sufficient force

What did Gottfried Leibniz contribute?

He reasoned that whatever caused the ball in a Newton's cradle to move resembled a force that seemed to be transmitted through the balls. He called this physical quantity vis viva. The term "energy" wasn't used until the 1850s.

If work is done on an object by a person, what happens to the energy in the person and the object?

If work is being done, the person doing work must lose energy. This energy is then transferred to the object, and as a result the object gains energy.

Who discovered that electricity can produce magnetism?

If you hold a magnet above iron fillings, the filings move toward the magnet, indicating that magnetism is a form of energy. In 1820, a Danish physicist and philosopher Hans Oersted. He discovered that an electric current in a wire could produce magnetic effects. By accident, he passed a metal wire that had a current passing through it over a compass. As he did this, he noticed that the compass needle moved. This change in the needle's position showed that electricity can produce magnetism. This discovery led to the invention of the electromagnet.

What does the second law of thermodynamic states?

If you place a hot-water bottle in your bed, the bed will warm up and the hotwater bottle will slowly cool down. Eventually, the bottle and the bed will reach the same temperature. The heat transfers from the bottle to the bed, so the total amount of energy in the bottle and bed remains constant. This is consistent with the first law of thermodynamics, but it also illustrates the second law of thermodynamics, which describes the direction of energy flow in natural processes. The second law states that heat always flows naturally from a hot object to a cold object, but never naturally from a cold object to a hot object During this transfer, it can be made to do work, but of course some energy is lost due to its surroundings.

Who first realized that heat and mechanical energy were related?

In 1800 by Benjamin Thompson, who later became Count Runtford, the minister of war in Bavaria. -noticed that a huge amount of heat was generated in the bored metal, and suggested that heat could be manufactured by the motion of the workers.

What did Thomas Seebeck contribute?

In 1821, an estonian-German physicist Thomas Seebeck took a strip of one type of metal and joined it ends to a strip of another type of metal to form a loop. He heated one of the junctions of the two metals and kept the other cold. The difference in temperature between the junctions caused the electrons inside the metal to move, producing an electric current. The magnetic field created by the current caused a compass needle to move. This experiment was evidence that heat could be converted into electricity.

What did Michael Faraday contribute?

In 1831 he showed that the reverse can happen. He moved a magnet through a coil of wire and observed that this caused an electric current to flow through the wire.

What did Henri Becquerel contribute?

In France 1896, he observed that certain atoms spontaneously disintegrate, and in the process, emit radiation or radiant energy.

How does a CANDU nuclear reactor work?

In the reactor, uranium disintegrates during nuclear fission, releasing nuclear energy as radiation. This radiation is converted to thermal energy, which is used to heat water to steam. Under pressure, the steam is then piped into the turbines and causes them to move. The steam's kinetic energy is converted into the turbines' kinetic energy. The turbines turn a coil of wire in a magnetic field. This converts the turbines' kinetic energy into electrical energy. This sequence of energy conversions is very similar to the conversions in a coalburning power station. In fact, nuclear power stations and coal-burning power stations are both thermal power stations. They create heat to produce steam, which drives the turbines. Power stations powered by natural gas are also thermal power stations.

What are the disadvantages of the Archimedes screw or the Persian wheel, and as well as the reciprocating pump?

It could do lift the water very far because of the downward force of the water

How does a fuel cell work?

Like a solar cell, a hydrogen fuel cell operates like a battery. In fact, it's known as the new, improved battery. It converts the chemical energy in a fuel, such as hydrogen, into electrical energy. However, unlike a battery, it does not require recharging. It will produce electrical energy as long as it has fuel. The byproducts of the hydrogen fuel cell are water and heat. This is why the hydrogen fuel cell is so popular in spacecraft. Not only can the fuel cell supply the necessary electricity to maintain all the electrical instruments on board the spacecraft, but it can also supply all the heat and water necessary for the trip, from the "waste" products of the cell's reaction.

What happened in 1867?

N.A.Otto and Eugen Langen developed the four-stroke internal combustion engine. Drawback: it used coal as fuel, which doesn't burn very hot.

What is the unit for force?

Newtons, kg multiply by m/s^2

Who was Thomas Newcomen?

Patented the next heat engine which also uses steam as the driving force. -uses a boiler to produce steam to move a piston in a separate pump. Drawback: could pump water much higher but the process was inefficient and required large amounts of heat.

What is solar energy?

Solar energy results from a hydrogen-hydrogen nuclear fusion reaction with the release of nuclear energy. This radiant energy travels to Earth as electromagnetic radiation. It is converted to other forms of energy such as heat, The hydrogen-hydrogen nuclear fusion reaction that occurs at the centre of the sun releases tremendous amounts of solar energy that travels to Earth as electromagnetic waves. When this radiation strikes Earth, it's either absorbed by Earth or reflected back into space. -radiant energy from the sun emitted by the hydrogen-hydrogen nuclear fusion reaction that occurs in the sun's core. This energy travels through space as electromagnetic radiation and captured by plant through photosynthesis.

How can you prevent the balls in Newton's cradle from stopping?

That would only happen in a vacuum where no sound, heat, or friction occur, this system would continue forever. However, due to friction from the string and air resistance and heat transfer from contact, energy will be lost. -if it were in a vacuum it could go on forever. A vacuum, like space, would have no friction and other opposing forces acting on the cradle so no energy would be lost. 

How does a hydro-electric power station work?

The hydrogen-hydrogen nuclear fusion reaction that occurs at the centre of the Sun releases tremendous amounts of solar energy that travels to Earth as electromagnetic waves. When this radiation strikes Earth, it is either absorbed by Earth or reflected back into space. When light energy from the Sun strikes the chlorophyll in plants, a chemical reaction, photosynthesis, occurs that converts carbon dioxide and water into glucose and oxygen. The glucose contains chemical potential energy. When animals eat plants, this chemical potential energy in the glucose is released through the process of respiration in the animals' bodies. Glucose (sugar) from food reacts with oxygen in animal cells to produce carbon dioxide and water. The energy released during respiration, in the form of adenosine triphosphate (ATP), provides the energy necessary for the animal to carry out life functions. It also produces heat.

What are some of the energy conversions in natural system?

The hydrogen-hydrogen nuclear fusion reaction that occurs at the centre of the Sun releases tremendous amounts of solar energy that travels to Earth as electromagnetic waves. When this radiation strikes Earth, it is either absorbed by Earth or reflected back into space. When light energy from the Sun strikes the chlorophyll in plants, a chemical reaction, photosynthesis, occurs that converts carbon dioxide and water into glucose and oxygen. The glucose contains chemical potential energy. When animals eat plants, this chemical potential energy in the glucose is released through the process of respiration in the animals' bodies. Glucose (sugar) from food reacts with oxygen in animal cells to produce carbon dioxide and water. The energy released during respiration, in the form of adenosine triphosphate (ATP), provides the energy necessary for the animal to carry out life functions. It also produces heat.

What is the definition of heat?

The transfer of this thermal energy from a hot object to a cold object

Who invented the first battery?

The volta pile-the first battery- was invented by Italian physicist Alessandro Volta in the early 1800s.

What two experiment did Joules do?

This experiment supports connection between potenntial energy and heat. As the masses fall, the wheel rotates, heating up the water. If the masses are increased, there is a proportional increase in the amount of heat produced, and thus a proportional increase in the water temperature. -As the masses fall, they lose Gravitational potential energy. The paddle has work done to it so it gains the energy the masses lose, in the form of KE, which is then transformed into heat. This experiment supports a connection between KE and heat. In this experiment, a block of wood is in motion and so has KE as it falls. However, it loses KE when it collides with the other block. During the collision, the temperature of the other block increases. When the speed of the falling block is increased, its KE is also increased, and a corresponding temperature happens in the other block. As one block collides with the other, the first loses KE and the second one gains this energy in the form of heat.

What is elastic potential energy?

This is a situation in which a force can be applied against an opposing force, resulting in a change in potential energy. If a force is used to stretch an elastic, the force acts against the elastic force of the material. This results in a change in the shape of the elastic and in energy being stored. This energy is called elastic potential energy. This is also the type of energy stored in a stretch or compressed spring, a trampoline, or a spring diving board. These are all examples of work being done by applying a force through a distance against an opposing force, which results in an energy transfer to the object. This energy is then stored in the object as potential energy. If work is done on an elastic, the elastic gains EPE. When the elastic is released, the cork is propelled vertically into the air. The EPE is converted into KE of the cork. As the cork rises, the KE is converted into GPE. If no energy is lost, then the initial work done should equal the EPE. The EPE should, in turn, equal to the GPE.

What is the theory behind Newton's cradles?

When a ball on one end of the cradle is pulled away from the others and then released, it strikes the next ball in the cradle, which remains motionless. But the ball on the opposite end of the row is thrown into the air, then swings back to strike the other balls, starting the chain reaction again in reverse. Newton's Cradle aptly demonstrates the principle of the conservation of momentum (mass times speed). This principle states that when two objects collide, the total momentum of the objects before the collision is equal to the total momentum of the objects after the collision. In other words, when the first ball of Newton's Cradle collides with the second, the first ball stops, but its momentum isn't lost, just transferred to the second ball, then the third, then the fourth, until it reaches the very last ball. You witness this conservation of momentum as the last ball swings into the air with nearly the same momentum as the first ball. Thus, if two balls are lifted into the air on one end of the device and released, then two balls on the opposite end will swing in response. This continuous clicking of balls is also proof of Newton's law of the conservation of energy, which states that energy can't be created or destroyed but that it can change forms. Newton's Cradle demonstrates this last part of the law quite well, as it converts the potential energy of one ball into kinetic energy that is transferred down the line of balls and ultimately results in the upward swinging of the last ball.

What is work input?

When a force is applied to move an object through a distance, work is done on the object

What is water energy?

When surface water is heated by the sun, which cause evaporation of water into the atmosphere and condenses forming rain. Rain creates flowing water in streams and rivers which can then be converted into other forms of energy.

Describe the energy transfer taken place when an archer draw back on the string of the bow to shoot an arrow into the air.

When the person pulls the bow string, an average force is being exerted through a distance, and work is being done. This work is stored in the bow as EPE. When the string is released, EPE is converted into KE, as the arrow is released. As the arrow rises into the air, it slows down and loses KE, but it is rising higher above the surface of earth, and so gains GPE. This illustrates that PE can be converted into KE and KE into PE.

Is work scalar or vector quantity?

Work is scalar because it is a form of energy, and energy has no direction.

Are work and energy the same thing?

Yes, if a body does work on an object. then the body doing the work loses energy, and the object that has work done to it gains energy. ex) a pool cue loses energy as it hits a ball, and the ball, once hit, gains the energy the cue loses. An energy transfer has ocured.

What did Gottlieb Daimler contribute?

he designed a petroleum-fuelled internal combustion engine that used gasoline instead of coal gas and it burns much hotter.

What is terminal velocity?

As an object falls, it picks up speed. The increase in speed leads to an increase in the amount of air resistance. Eventually, the force of air resistance becomes large enough to balances the force of gravity. At this instant in time, the net force is 0 Newton; the object will stop accelerating. The object is said to have reached a terminal velocity. The change in velocity terminates as a result of the balance of forces. The velocity at which this happens is called the terminal velocity.

Suppose that you filled a baking dish to the rim with water and walked around an oval track making an attempt to complete a lap in the least amount of time. The water would have a tendency to spill from the container during specific locations on the track. In general the water spilled when:

-the container was at rest and you attempted to move it -the container was in motion and you attempted to stop it -the container was moving in one direction and you attempted to change its direction. The water spills whenever the state of motion of the container is changed. The water resisted this change in its own state of motion. The water tended to "keep on doing what it was doing." The container was moved from rest to a high speed at the starting line; the water remained at rest and spilled onto the table. The container was stopped near the finish line; the water kept moving and spilled over container's leading edge. The container was forced to move in a different direction to make it around a curve; the water kept moving in the same direction and spilled over its edge. The behavior of the water during the lap around the track can be explained by Newton's first law of motion.

What are the factors affecting the amount of Egravitional an object has?

-the height, greater the height, the more potential energy it has -the mass, the greater the mass, the more potential energy it has -If an object is lifted, work is done against gravitational force. The object gains energy.

What is mechanical energy?

-the sum of the energy of motion and position In all instances, an object that possesses some form of energy supplies the force to do the work. In the instances described here, the objects doing the work (a student, a tractor, a pitcher, a motor/chain) possess chemical potential energy stored in food or fuel that is transformed into work. In the process of doing work, the object that is doing the work exchanges energy with the object upon which the work is done. When the work is done upon the object, that object gains energy. The energy acquired by the objects upon which work is done is known as mechanical energy. Mechanical energy is the energy that is possessed by an object due to its motion or due to its position. Mechanical energy can be either kinetic energy (energy of motion) or potential energy (stored energy of position). Objects have mechanical energy if they are in motion and/or if they are at some position relative to a zero potential energy position (for example, a brick held at a vertical position above the ground or zero height position). A moving car possesses mechanical energy due to its motion (kinetic energy). A moving baseball possesses mechanical energy due to both its high speed (kinetic energy) and its vertical position above the ground (gravitational potential energy). A World Civilization book at rest on the top shelf of a locker possesses mechanical energy due to its vertical position above the ground (gravitational potential energy). A barbell lifted high above a weightlifter's head possesses mechanical energy due to its vertical position above the ground (gravitational potential energy). A drawn bow possesses mechanical energy due to its stretched position (elastic potential energy). An object that possesses mechanical energy is able to do work. In fact, mechanical energy is often defined as the ability to do work. Any object that possesses mechanical energy - whether it is in the form of potential energy or kinetic energy - is able to do work. That is, its mechanical energy enables that object to apply a force to another object in order to cause it to be displaced. Numerous examples can be given of how an object with mechanical energy can harness that energy in order to apply a force to cause another object to be displaced. A classic example involves the massive wrecking ball of a demolition machine. The wrecking ball is a massive object that is swung backwards to a high position and allowed to swing forward into building structure or other object in order to demolish it. Upon hitting the structure, the wrecking ball applies a force to it in order to cause the wall of the structure to be displaced. The diagram below depicts the process by which the mechanical energy of a wrecking ball can be used to do work. The massive ball of a demolition machine possesses mechanical energy- the ability to do work. When held at a height, it possesses mechanical energy in the form of potential energy. As it falls, it exhibits mechanical energy in the form of kinetic energy. As it strikes the structure to be demolished, it applies a force to displace the structure, it does work upon the structure. A hammer is a tool that utilizes mechanical energy to do work. The mechanical energy of a hammer gives the hammer its ability to apply a force to a nail in order to cause it to be displaced. Because the hammer has mechanical energy (in the form of kinetic energy), it is able to do work on the nail. Mechanical energy is the ability to do work. Another example that illustrates how mechanical energy is the ability of an object to do work can be seen any evening at your local bowling alley. The mechanical energy of a bowling ball gives the ball the ability to apply a force to a bowling pin in order to cause it to be displaced. Because the massive ball has mechanical energy (in the form of kinetic energy), it is able to do work on the pin. Mechanical energy is the ability to do work. A dart gun is still another example of how mechanical energy of an object can do work on another object. When a dart gun is loaded and the springs are compressed, it possesses mechanical energy. The mechanical energy of the compressed springs gives the springs the ability to apply a force to the dart in order to cause it to be displaced. Because of the springs have mechanical energy (in the form of elastic potential energy), it is able to do work on the dart. Mechanical energy is the ability to do work. A common scene in some parts of the countryside is a "wind farm." High-speed winds are used to do work on the blades of a turbine at the so-called wind farm. The mechanical energy of the moving air gives the air particles the ability to apply a force and cause a displacement of the blades. As the blades spin, their energy is subsequently converted into electrical energy (a non-mechanical form of energy) and supplied to homes and industries in order to run electrical appliances. Because the moving wind has mechanical energy (in the form of kinetic energy), it is able to do work on the blades. Once more, mechanical energy is the ability to do work. When energy is transferred to an object, it can cause a change in both the KE and PE simultaneously. A ball thrown upward has KE because of its motion, and also has PE because of its postion above the surface of earth. As a result, they are combined as a general type of energy called mechanical energy. mechanical energy= kinetic energy+ potential energy

What are the two scenarios that are negative acceleration?

1. the change in the magnitude of the velocity is negative but the direction is positive. 2. the change in the magnitude of the velocity is positive but the direction is negative

Average velocity

A uniform motion that involves changing a position in a specified time. To determine the average velocity quantitatively, use the following equation: Average velocity= displacement/time elapsed *Must state its magnitude and direction.

How is a scalar quantity written differently from a vector quantity?

A vector quantity is written with a vector arrow above the symbol for the measured quantity. For example, the symbol for speed is v, and the symbol for velocity is v with an arrow on it.

Which type of appliance would convert electrical energy into sound energy?

A.amplifier B.microphone c.speaker correct answer: speaker A speaker converts electrical energy into sound energy which we can then hear. An amplifier increases the sound energy. A microphone converts sound energy into electrical energy.

What are the factors that kinetic energy depends on?

All moving objects have KE. The KE an object has depends on its: mass - if the mass doubles, the KE doubles speed - if the speed doubles, the KE quadruples (increases four times)

Do some objects have more of a tendency to resist changes than others?

All objects resist changes in their state of motion. All objects have this tendency - they have inertia. But do some objects have more of a tendency to resist changes than others? Absolutely yes! The tendency of an object to resist changes in its state of motion varies with mass. Mass is that quantity that is solely dependent upon the inertia of an object. The more inertia that an object has, the more mass that it has. A more massive object has a greater tendency to resist changes in its state of motion. Suppose that there are two seemingly identical bricks at rest on the physics lecture table. Yet one brick consists of mortar and the other brick consists of Styrofoam. Without lifting the bricks, how could you tell which brick was the Styrofoam brick? You could give the bricks an identical push in an effort to change their state of motion. The brick that offers the least resistance is the brick with the least inertia - and therefore the brick with the least mass (i.e., the Styrofoam brick). A common physics demonstration relies on this principle that the more massive the object, the more that object resist changes in its state of motion. The demonstration goes as follows: several massive books are placed upon a teacher's head. A wooden board is placed on top of the books and a hammer is used to drive a nail into the board. Due to the large mass of the books, the force of the hammer is sufficiently resisted (inertia). This is demonstrated by the fact that the teacher does not feel the hammer blow. (Of course, this story may explain many of the observations that you previously have made concerning your "weird physics teacher.") A common variation of this demonstration involves breaking a brick over the teacher's hand using the swift blow of a hammer. The massive bricks resist the force and the hand is not hurt.

What does Newton's first law of motion states?

An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. If the resultant force is zero, a moving object will stay at the same speed. If there is no resultant force then a system is said to be in equilibrium. if its unbalanced force: -it will speed up if the resultant force is in the same direction as the object is moving -it will slow down if the resultant force is in the opposite direction The behavior of all objects can be described by saying that objects tend to "keep on doing what they're doing" (unless acted upon by an unbalanced force). If at rest, they will continue in this same state of rest. If in motion with an eastward velocity of 5 m/s, they will continue in this same state of motion (5 m/s, East). If in motion with a leftward velocity of 2 m/s, they will continue in this same state of motion (2 m/s, left). The state of motion of an object is maintained as long as the object is not acted upon by an unbalanced force. All objects resist changes in their state of motion - they tend to "keep on doing what they're doing." The behavior of all objects can be described by saying that objects tend to "keep on doing what they're doing" (unless acted upon by an unbalanced force). If at rest, they will continue in this same state of rest. If in motion with an eastward velocity of 5 m/s, they will continue in this same state of motion (5 m/s, East). If in motion with a leftward velocity of 2 m/s, they will continue in this same state of motion (2 m/s, left). The state of motion of an object is maintained as long as the object is not acted upon by an unbalanced force. All objects resist changes in their state of motion - they tend to "keep on doing what they're doing." -According to Newton's first law, an object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. It is the natural tendency of objects to keep on doing what they are doing. All objects resist changes in their state of motion. In the absence of an unbalanced force, an object in motion will maintain its state of motion. This is often called the law of inertia. Newton's first law of motion predicts the behavior of objects for which all existing forces are balanced. The first law - sometimes referred to as the law of inertia - states that if the forces acting upon an object are balanced, then the acceleration of that object will be 0 m/s/s. Objects at equilibrium (the condition in which all forces balance) will not accelerate. According to Newton, an object will only accelerate if there is a net or unbalanced force acting upon it. The presence of an unbalanced force will accelerate an object - changing its speed, its direction, or both its speed and direction.

What is potential energy?

An object can store energy as the result of its position. For example, the heavy ball of a demolition machine is storing energy when it is held at an elevated position. This stored energy of position is referred to as potential energy. Similarly, a drawn bow is able to store energy as the result of its position. When assuming its usual position (i.e., when not drawn), there is no energy stored in the bow. Yet when its position is altered from its usual equilibrium position, the bow is able to store energy by virtue of its position. This stored energy of position is referred to as potential energy. Potential energy is the stored energy of position possessed by an object. *Kinetic energy is not potential energy* To summarize, potential energy is the energy that is stored in an object due to its position relative to some zero position. An object possesses gravitational potential energy if it is positioned at a height above (or below) the zero height. An object possesses elastic potential energy if it is at a position on an elastic medium other than the equilibrium position. -the stored energy because of its position relative to some other object, it is called potential energy because it has the potential to do work. Potential energy is energy that is stored in readiness. The type of potential energy depends on how the energy is stored.

A 2-kg object is moving horizontally with a speed of 4 m/s. How much net force is required to keep the object moving at this speed and in this direction?

An object in motion will maintain its state of motion. The presence of an unbalanced force changes the velocity of the object.

Is constant acceleration and constant velocity the same thing?

An object with a constant acceleration should not be confused with an object with a constant velocity. Don't be fooled! If an object is changing its velocity -whether by a constant amount or a varying amount - then it is an accelerating object. And an object with a constant velocity is not accelerating. -Since accelerating objects are constantly changing their velocity, one can say that the distance traveled/time is not a constant value.

Two students are discussing their physics homework prior to class. They are discussing an object that is being acted upon by two individual forces (both in a vertical direction); the free-body diagram for the particular object is shown at the right. During the discussion, Anna Litical suggests to Noah Formula that the object under discussion could be moving. In fact, Anna suggests that if friction and air resistance could be ignored (because of their negligible size), the object could be moving in a horizontal direction. According to Anna, an object experiencing forces as described at the right could be experiencing a horizontal motion as described below. Noah Formula objects, arguing that the object could not have any horizontal motion if there are only vertical forces acting upon it. Noah claims that the object must be at rest, perhaps on a table or floor. After all, says Noah, an object experiencing a balance of forces will be at rest. Who do you agree with?

Anna is correct. Noah Formula may know his formulas but he does not know (or does not believe) Newton's laws. If the forces acting on an object are balanced and the object is in motion, then it will continue in motion with the same velocity. Remember: forces do not cause motion. Forces cause accelerations.

What is the total mechanical energy refers to?

As already mentioned, the mechanical energy of an object can be the result of its motion (i.e., kinetic energy) and/or the result of its stored energy of position (i.e., potential energy). The total amount of mechanical energy is merely the sum of the potential energy and the kinetic energy. This sum is simply referred to as the total mechanical energy (abbreviated TME). TME = PE + KE As discussed earlier, there are two forms of potential energy discussed in our course - gravitational potential energy and elastic potential energy. Given this fact, the above equation can be rewritten: TME = PEgrav + PEspring + KE Merely remember that total mechanical energy is the energy possessed by an object due to either its motion or its stored energy of position. The total amount of mechanical energy is merely the sum of these two forms of energy. And finally, an object with mechanical energy is able to do work on another object.

What is the difference between weight and mass?

As mentioned above, the force of gravity acting upon an object is sometimes referred to as the weight of the object. Many students of physics confuse weight with mass. The mass of an object refers to the amount of matter that is contained by the object; the weight of an object is the force of gravity acting upon that object. Mass is related to how much stuff is there and weight is related to the pull of the Earth (or any other planet) upon that stuff. The mass of an object (measured in kg) will be the same no matter where in the universe that object is located. Mass is never altered by location, the pull of gravity, speed or even the existence of other forces. For example, a 2-kg object will have a mass of 2 kg whether it is located on Earth, the moon, or Jupiter; its mass will be 2 kg whether it is moving or not (at least for purposes of our study); and its mass will be 2 kg whether it is being pushed upon or not. On the other hand, the weight of an object (measured in Newton) will vary according to where in the universe the object is. Weight depends upon which planet is exerting the force and the distance the object is from the planet. Weight, being equivalent to the force of gravity, is dependent upon the value of g - the gravitational field strength. On earth's surface g is 9.8 N/kg (often approximated as 10 N/kg). On the moon's surface, g is 1.7 N/kg. Go to another planet, and there will be another g value. Furthermore, the g value is inversely proportional to the distance from the center of the planet.

What is an unbalanced force?

But what exactly is meant by the phrase unbalanced force? What is an unbalanced force? In pursuit of an answer, we will first consider a physics book at rest on a tabletop. There are two forces acting upon the book. One force - the Earth's gravitational pull - exerts a downward force. The other force - the push of the table on the book (sometimes referred to as a normal force) - pushes upward on the book. Since these two forces are of equal magnitude and in opposite directions, they balance each other. The book is said to be at equilibrium. There is no unbalanced force acting upon the book and thus the book maintains its state of motion. When all the forces acting upon an object balance each other, the object will be at equilibrium; it will not accelerate. An object is said to be acted upon by an unbalanced force only when there is an individual force that is not being balanced by a force of equal magnitude and in the opposite direction.

How does energy transfer takes place in a car?

Different forms of energy can be transferred from one form to another. Energy transfer diagrams show each form of energy - whether it is stored or not - and the processes taking place as energy is transferred. The energy transfer diagram below shows the useful energy transfer in a car engine. You can see that a car engine transfers chemical energy, which is stored in the fuel, into kinetic energy in the engine and wheels.

What is displacement and what type of quantity is it?

Displacement is a vector quantity. Displacement- a measurement of the change in distance and the direction or the change in position of an object from a reference point. *To determine the displacement, you need to know both the beginning and final position of the person, and the direction that she moved in.

What is the difference between distance traveled and displacement?

Distance traveled is a scalar quantity. It's a measurement of the change in distance of an object moving from a starting reference point. Displacement is a vector quantity. It is a measurement of the change in distance AND the direction or the change in position of an object from a reference point.

What is distance and what type of quantity is it?

Distance travelled is a scalar quantity. Distance-the measurement of the change in distance of an object moving from a starting reference point.

What is the law of conservation of energy?

Energy can be transferred usefully, stored or dissipated. It cannot be created or destroyed. This is called conservation of energy. -it states that the total amount of energy in a given situation remains constant. Energy can be converted from one form to another but the total amount of energy never changes. Thus, the total amount of ME remains constant. -energy cannot be created or destroyed. It can only be transformed from one form to another, and the total amount of energy never changes.

A physics teacher walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North. Find the displacement.

Even though the physics teacher has walked a total distance of 12 meters, her displacement is 0 meters. During the course of her motion, she has "covered 12 meters of ground" (distance = 12 m). Yet when she is finished walking, she is not "out of place" - i.e., there is no displacement for her motion (displacement = 0 m). Displacement, being a vector quantity, must give attention to direction. The 4 meters east cancels the 4 meters west; and the 2 meters south cancels the 2 meters north.

What is Newton's third law of motion?

For every action, there is an equal and opposite reaction. According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. There are two forces resulting from this interaction - a force on the chair and a force on your body. These two forces are called action and reaction forces and are the subject of Newton's third law of motion. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second object. The direction of the force on the first object is opposite to the direction of the force on the second object. Forces always come in pairs - equal and opposite action-reaction force pairs. A variety of action-reaction force pairs are evident in nature. Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. But a push on the water will only serve to accelerate the water. Since forces result from mutual interactions, the water must also be pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction force. Action-reaction force pairs make it possible for fish to swim.

How does volume change during a phrase change?

For most substances, the change from a solid to a liquid state does not mean a big change in volume. This is because the particles stay approximately the same distance apart. This means that the density of a substance, for example iron, does not change by much when it melts. When a liquid changes into a gas, the spacing between the particles increases significantly. This means that the gas takes up a lot more space than the liquid, so its volume increases dramatically. When a gas condenses to form a liquid, its volume decreases significantly.

What is a vector quantity?

It indicates "how much"(the magnitude) and the direction of the quantity -Velocity,displacement, acceleration, force are all vector quantities.

What did Galileo develop about the sense of inertia?

Galileo, a premier scientist in the seventeenth century, developed the concept of inertia. Galileo reasoned that moving objects eventually stop because of a force called friction. In experiments using a pair of inclined planes facing each other, Galileo observed that a ball would roll down one plane and up the opposite plane to approximately the same height. If smoother planes were used, the ball would roll up the opposite plane even closer to the original height. Galileo reasoned that any difference between initial and final heights was due to the presence of friction. Galileo postulated that if friction could be entirely eliminated, then the ball would reach exactly the same height. Galileo further observed that regardless of the angle at which the planes were oriented, the final height was almost always equal to the initial height. If the slope of the opposite incline were reduced, then the ball would roll a further distance in order to reach that original height. -this is because energy is not destroyed or created, if the ball had this amount of energy initially, if there were no friction, the ball should have the same energy at the end as well,but if there was friction, some energy will be lost due to friction and the ball would not rise up to as high as the starting point.

When a person diets, is their goal to lose mass or to lose weight? Explain.

Generally, people diet because they wish to reduce the amount of matter on their body - they wish to remove the blubber. So people diet to lose mass. If one wishes to lose weight, they could get a six fold reduction by moving to the moon. Groovy.

What are some of the everyday applications that involves Newton's first law of motion?

Have you ever experienced inertia (resisting changes in your state of motion) in an automobile while it is braking to a stop? The force of the road on the locked wheels provides the unbalanced force to change the car's state of motion, yet there is no unbalanced force to change your own state of motion. Thus, you continue in motion, sliding along the seat in forward motion. A person in motion stays in motion with the same speed and in the same direction ... unless acted upon by the unbalanced force of a seat belt. Yes! Seat belts are used to provide safety for passengers whose motion is governed by Newton's laws. The seat belt provides the unbalanced force that brings you from a state of motion to a state of rest. Perhaps you could speculate what would occur when no seat belt is used. -To dislodge ketchup from the bottom of a ketchup bottle, it is often turned upside down and thrusted downward at high speeds and then abruptly halted. -While riding a skateboard (or wagon or bicycle), you fly forward off the board when hitting a curb or rock or other object that abruptly halts the motion of the skateboard. -Headrests are placed in cars to prevent whiplash injuries during rear-end collisions.

2. A 4.0-kg object is moving across a friction-free surface with a constant velocity of 2 m/s. Which one of the following horizontal forces is necessary to maintain this state of motion?

If an object is in motion, then it will stay in motion with those very same motion characteristics. It doesn't take any force to maintain that same state of motion. In fact, the presence of a force would "ruin" such a state of motion and cause an acceleration.

What can you find from a distance-time graph?

If the graph is s straight line, this tells us that the change in distance traveled in relation to the time intervals s constant; therefore, the object has uniform motion. -if the line of best fit were a curve of any type, this would mean the object was changing distance traveled in equal time intervals. In other words the object would be either speeding up or slowing down -the slope of the line also tells you something about the motion. The slope of the line from the graph is rise over run, which in this case, is change in distance/ change in time. This slope is the exact formula for finding out the average speed. As a result, the slope of a distance-time graph is a visual representation of the speed of an object. A greater or steeper slope indicates a faster speed and a lesser slope indicates a slower speed.

Why does the elephant fall faster than the feather when dropping off a building, not considering air resistance.

In the absence of air resistance, both the elephant and the feather are in a state of free-fall. That is to say, the only force acting upon the two objects is the force of gravity. This force of gravity is what causes both the elephant and the feather to accelerate downwards. The force of gravity experienced by an object is dependent upon the mass of that object. Mass refers to the amount of matter in an object. Clearly, the elephant has more mass than the feather. Due to its greater mass, the elephant also experiences a greater force of gravity. That is, the Earth is pulling downwards upon the elephant with more force than it pulls downward upon the feather. Since weight is a measure of gravity's pull upon an object, it would also be appropriate to say that the elephant weighs more than the feather. For these reasons, all of the eight statements are false; there is an erroneous part to each statement due to the confusion of weight, mass, and force of gravity. But if the elephant weighs more and experiences a greater downwards pull of gravity compared to the feather, why then does it hit the ground at the same time as the feather? Great question!! To answer this question, we must recall Newton's second law - the law of acceleration. Newton's second law states that the acceleration of an object is directly related to the net force and inversely related to its mass. When figuring the acceleration of object, there are two factors to consider - force and mass. Applied to the elephant-feather scenario, we can say that the elephant experiences a much greater force (which tends to produce large accelerations. Yet, the mass of an object resists acceleration. Thus, the greater mass of the elephant (which tends to produce small accelerations) offsets the influence of the greater force. It is the force/mass ratio which determines the acceleration. Even though a baby elephant may experience 100 000 times the force of a feather, it has 100 000 times the mass. The force/mass ratio is the same for each. The greater mass of the elephant requires the greater force just to maintain the same acceleration as the feather. A simple rule to bear in mind is that all objects (regardless of their mass) experience the same acceleration when in a state of free fall. When the only force is gravity, the acceleration is the same value for all objects. On Earth, this acceleration value is 9.8 m/s/s. This is such an important value in physics that it is given a special name - the acceleration of gravity - and a special symbol - g.

What does the "unbalanced force" in Newton's first law of motion refers to?

In the statement of Newton's first law, the unbalanced force refers to that force that does not become completely balanced (or canceled) by the other individual forces. If either all the vertical forces (up and down) do not cancel each other and/or all horizontal forces do not cancel each other, then an unbalanced force exists. The existence of an unbalanced force for a given situation can be quickly realized by looking at the free-body diagram for that situation.

What is inertia?

Inertia is the tendency of an object to resist changes in its state of motion. But what is meant by the phrase state of motion? The state of motion of an object is defined by its velocity - the speed with a direction. Thus, inertia could be redefined as follows: Inertia: tendency of an object to resist changes in its velocity. An object at rest has zero velocity - and (in the absence of an unbalanced force) will remain with a zero velocity. Such an object will not change its state of motion (i.e., velocity) unless acted upon by an unbalanced force. An object in motion with a velocity of 2 m/s, East will (in the absence of an unbalanced force) remain in motion with a velocity of 2 m/s, East. Such an object will not change its state of motion (i.e., velocity) unless acted upon by an unbalanced force. Objects resist changes in their velocity. As learned in an earlier unit, an object that is not changing its velocity is said to have an acceleration of 0 m/s/s. Thus, we could provide an alternative means of defining inertia: Inertia: tendency of an object to resist acceleration.

What is the law of inertia?

It is commonly referred to Newton's first law of motion. The law of inertia is most commonly experienced when riding in cars and trucks. In fact, the tendency of moving objects to continue in motion is a common cause of a variety of transportation accidents - of both small and large magnitudes. Consider for instance a ladder strapped to the top of a painting truck. As the truck moves down the road, the ladder moves with it. Being strapped tightly to the truck, the ladder shares the same state of motion as the truck. As the truck accelerates, the ladder accelerates with it; as the truck decelerates, the ladder decelerates with it; and as the truck maintains a constant speed, the ladder maintains a constant speed as well. But what would happen if the ladder was negligently strapped to the truck in such a way that it was free to slide along the top of the truck? Or what would happen if the straps deteriorated over time and ultimately broke, thus allowing the ladder to slide along the top of the truck? Supposing either one of these scenarios were to occur, the ladder may no longer share the same state of motion as the truck. With the strap present, the forces exerted upon the car are also exerted upon the ladder. The ladder undergoes the same accelerated and decelerated motion that the truck experiences. Yet, once the strap is no longer present, the ladder is more likely to maintain its state of motion. The animation below depicts a possible scenario. If the truck were to abruptly stop and the straps were no longer functioning, then the ladder in motion would continue in motion. Assuming a negligible amount of friction between the truck and the ladder, the ladder would slide off the top of the truck and be hurled into the air. Once it leaves the roof of the truck, it becomes a projectile and continues in projectile-like motion.

What is the unit for work

Joules, kg multiple by m^2 divided by s^2

What is kinetic energy?

Kinetic energy is the energy of motion. An object that has motion - whether it is vertical or horizontal motion - has kinetic energy. he amount of translational kinetic energy (from here on, the phrase kinetic energy will refer to translational kinetic energy) that an object has depends upon two variables: the mass (m) of the object and the speed (v) of the object. The following equation is used to represent the kinetic energy (KE) of an object. KE = 0.5 • m • v2 where m = mass of object v = speed of object This equation reveals that the kinetic energy of an object is directly proportional to the square of its speed. That means that for a twofold increase in speed, the kinetic energy will increase by a factor of four. For a threefold increase in speed, the kinetic energy will increase by a factor of nine. And for a fourfold increase in speed, the kinetic energy will increase by a factor of sixteen. The kinetic energy is dependent upon the square of the speed. As it is often said, an equation is not merely a recipe for algebraic problem solving, but also a guide to thinking about the relationship between quantities. Kinetic energy is a scalar quantity; it does not have a direction. Unlike velocity, acceleration, force, and momentum, the kinetic energy of an object is completely described by magnitude alone. Like work and potential energy, the standard metric unit of measurement for kinetic energy is the Joule. As might be implied by the above equation, 1 Joule is equivalent to 1 kg*(m/s)^2. 1 Joule = 1 kg • m2/s2 -a faster speed results in a higher kinetic energy

A diver experiences a horizontal reaction force exerted by the blocks upon her feet at start of the race. Change PE or KE or Both？

Kinetic energy. The applied force of the starting blocks causes the diver to gain speed. Thus, the external force alters the kinetic energy of the diver. (NOTE: there is another force - gravity - which changes the diver's height; but the blocks are not responsible for this height change.)

What does it actually mean when an object has a constant speed?

Moving objects don't always travel with erratic and changing speeds. Occasionally, an object will move at a steady rate with a constant speed. That is, the object will cover the same distance every regular interval of time. For instance, a cross-country runner might be running with a constant speed of 6 m/s in a straight line for several minutes. If her speed is constant, then the distance traveled every second is the same. The runner would cover a distance of 6 meters every second. If we could measure her position (distance from an arbitrary starting point) each second, then we would note that the position would be changing by 6 meters each second. This would be in stark contrast to an object that is changing its speed. An object with a changing speed would be moving a different distance each second. The data tables below depict objects with constant and changing speed.

What does an acceleration of -2 m/s actually means?

Negative accelerations do not refer acceleration values that are less than 0. An acceleration of -2 m/s/s is an acceleration with a magnitude of 2 m/s/s that is directed in the negative direction.

What does Newton's second law of motion states?

Newton's second law of motion pertains to the behavior of objects for which all existing forces are not balanced. The second law states that the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object. The acceleration of an object depends directly upon the net force acting upon the object, and inversely upon the mass of the object. As the force acting upon an object is increased, the acceleration of the object is increased. As the mass of an object is increased, the acceleration of the object is decreased. -the direction of the object's acceleration is the same as the direction of the unbalanced force

Is energy required for a ball to maintain uniform motion?

No energy input is required.

A waiter carries a tray full of meals above his head by one arm straight across the room at constant speed. (Careful! This is a very difficult question that will be discussed in more detail later.)

No, This is not an example of work. There is a force (the waiter pushes up on the tray) and there is a displacement (the tray is moved horizontally across the room). Yet the force does not cause the displacement. To cause a displacement, there must be a component of force in the direction of the displacement.

Is coasting on a bicycle considered doing work?

No, because even though there is movement, the person is not applying a horizontal force to the bike.

Is carrying a backpack be considered doing work?

No, the person is not doing any work on a pack when she's carrying it parallel to the ground because the force of her hand on the pack is vertical and the distance the pack travels is horizontal.

Is there air resistance in space?

Note that in space and other vacuums there is no air resistance

7. A student with a mass of 80.0 kg runs up three flights of stairs in 12.0 sec. The student has gone a vertical distance of 8.0 m. Determine the amount of work done by the student to elevate his body to this height. Assume that his speed is constant.

REMEMBER: MASS IS NOT THE SAME THING AS WEIGHT The student weighs 784 N (Fgrav= 80 kg * 9.8 m/s/s). To lift a 784-Newton person at constant speed, 784 N of force must be applied to it (Newton's laws). The force is up, the displacement is up, and so the angle theta in the work equation is 0 degrees. Thus, W = (784 N) * (8 m) * cos (0 degrees) = 6272 Joules

What is the difference between average speed and instantaneous speed?

Since a moving object often changes its speed during its motion, it is common to distinguish between the average speed and the instantaneous speed. The distinction is as follows. Instantaneous Speed - the speed at any given instant in time. Average Speed - the average of all instantaneous speeds; found simply by a distance/time ratio. You might think of the instantaneous speed as the speed that the speedometer reads at any given instant in time and the average speed as the average of all the speedometer readings during the course of the trip. Since the task of averaging speedometer readings would be quite complicated (and maybe even dangerous), the average speed is more commonly calculated as the distance/time ratio.

What is the difference between speed and velocity?

Speed is a rate of change in distance whereas velocity is the rate of change in displacement. Speed only has a magnitude but velocity has a magnitude and a direction. - Speed is a scalar quantity that refers to "how fast an object is moving." Speed can be thought of as the rate at which an object covers distance. -Velocity is a vector quantity that refers to "the rate at which an object changes its position."

What is one misconception about acceleration?

Sports announcers will occasionally say that a person is accelerating if he/she is moving fast. Yet acceleration has nothing to do with going fast. A person can be moving very fast and still not be accelerating. Acceleration has to do with changing how fast an object is moving. If an object is not changing its velocity, then the object is not accelerating.

What are the three stages of falling?

When an object is dropped, there are three stages before it hits the ground: 1.At the start, the object accelerates downwards because of its weight. There is very little air resistance. There is a resultant force acting downwards. The acceleration is constant when the object is close to Earth. 2.As it gains speed, the object's weight stays the same but the air resistance on it increases. There is a resultant force acting downwards. 3.Eventually, the object's weight is balanced by the air resistance. There is no resultant force and the object reaches a steady speed - this is known as the terminal velocity.

What is a reference point

When you compare the object's position to another point. This point is called a reference point. Location from which we compare. -And all observations are made in relation to that point.

How do you move a ball at rest?

When you push on it because then you will create an unbalanced force, the force acting in one direction is greater than the force acting in the opposite direction.

It was stated that the acceleration of a free-falling object (on earth) is 9.8 m/s/s. This value (known as the acceleration of gravity) is the same for all free-falling objects regardless of how long they have been falling, or whether they were initially dropped from rest or thrown up into the air. Yet the questions are often asked "doesn't a more massive object accelerate at a greater rate than a less massive object?" "Wouldn't an elephant free-fall faster than a mouse?" This question is a reasonable inquiry that is probably based in part upon personal observations made of falling objects in the physical world. After all, nearly everyone has observed the difference in the rate of fall of a single piece of paper (or similar object) and a textbook. The two objects clearly travel to the ground at different rates - with the more massive book falling faster.

The answer to the question (doesn't a more massive object accelerate at a greater rate than a less massive object?) is absolutely not! That is, absolutely not if we are considering the specific type of falling motion known as free-fall. Free-fall is the motion of objects that move under the sole influence of gravity; free-falling objects do not encounter air resistance. More massive objects will only fall faster if there is an appreciable amount of air resistance present. (An lighter object will fall slower because it will encounter more air resistance due its small weight, but an heavier object will fall faster because it will encounter less air resistance due to its large weight, overcoming the air resistance).

A baseball is traveling upward towards a man in the bleachers. Is this Epotential to Egravity or Egravity to Epotential?

The ball is gaining height (rising) and losing speed (slowing down). Thus, the internal or conservative force (gravity) transforms the energy from KE (speed) to PE (height).

Two bricks are resting on edge of the lab table. Shirley Sheshort stands on her toes and spots the two bricks. She acquires an intense desire to know which of the two bricks are most massive. Since Shirley is vertically challenged, she is unable to reach high enough and lift the bricks; she can however reach high enough to give the bricks a push. Discuss how the process of pushing the bricks will allow Shirley to determine which of the two bricks is most massive. What difference will Shirley observe and how can this observation lead to the necessary conclusion?

The bricks, like any object, possess inertia. That is, the bricks will resist changes in their state of motion. If Shirley gives them a push, then the bricks will offer resistance to this push. The one with the most mass will be the one with the most inertia. This will be the brick which offers the most resistance. This very method of detecting the mass of an object can be used on Earth as well as in locations where gravitational forces are negligible for bricks.

What is acceleration?

The change in velocity during a specific time interval. *It is vector because it involves velocity* -An object is accelerating if it is changing its velocity.

A man runs after a bus. The bus is travelling at an average speed of 5 m/s. The man runs 25 m in 6 s. Does he catch the bus?

The man's average speed is 25 ÷ 6 = 4.2 m/s. So he will not catch a bus moving at 5 m/s.

How does energy transfer takes place in an electric lamp?

The next diagram shows the energy transfer diagram for the useful energy transfer in an electric lamp. You can see that the electric lamp transfers or converts electrical energy into light energy. Note that these energy transfer diagrams only show the useful energy transfers. However, car engines are also noisy and hot, and electric lamps also give out heat energy.

What is a scalar quantity?

The one that only indicates "how much"(the magnitude) of the quantity. -Speed, distance travelled are scalar quantities

What is the relationship between work and mechanical energy?

The quantitative relationship between work and mechanical energy is expressed by the following equation: TMEi + Wext = TMEf The equation states that the initial amount of total mechanical energy (TMEi) plus the work done by external forces (Wext) is equal to the final amount of total mechanical energy (TMEf). A few notes should be made about the above equation. First, the mechanical energy can be either potential energy (in which case it could be due to springs or gravity) or kinetic energy. Given this fact, the above equation can be rewritten as KEi + PEi + Wext = KEf + PEf The second note that should be made about the above equation is that the work done by external forces can be a positive or a negative work term. Whether the work term takes on a positive or a negative value is dependent upon the angle between the force and the motion. Recall from Lesson 1 that the work is dependent upon the angle between the force and the displacement vectors. If the angle is 180 degrees as it occasionally is, then the work term will be negative. If the angle is 0 degrees, then the work term will be positive.

What does the slope of a position-time graph(NOT distance-time graph)tells us?

The slope of the position vs. time graph is the average velocity for that object. And the slope of the distance vs. time graph is the average SPEED for that object.

What is work?

Whenever a force moves an object through a distance that is in the direction of the force, then work is done on the object. work= force x distance the object travels joule= newton x metre 1 J= 1 N x m

How can the mechanical energy be changed?

Whenever work is done upon an object by an external force, there will be a change in the total mechanical energy of the object. If only internal forces are doing work (no work done by external forces), there is no change in total mechanical energy; the total mechanical energy is said to be conserved. Because external forces are capable of changing the total mechanical energy of an object, they are sometimes referred to as nonconservative forces. Because internal forces do not change the total mechanical energy of an object, they are sometimes referred to as conservative forces. In this part of Lesson 2, we will further explore the quantitative relationship between work and energy. Internal: Fgravity, Fspring External: Fapplied, Ffriction, Fair, Ftension, Fnormal

What are the two most common factors that have a direct effect upon the amount of air resistance

The speed of the object and the cross-sectional area of the object. Increased speeds result in an increased amount of air resistance. As a skydiver falls, he accelerates downwards, gaining speed with each second. The increase in speed is accompanied by an increase in air resistance (as observed in the animation below). This force of air resistance counters the force of gravity. As the skydiver falls faster and faster, the amount of air resistance increases more and more until it approaches the magnitude of the force of gravity. Once the force of air resistance is as large as the force of gravity, a balance of forces is attained and the skydiver no longer accelerates. The skydiver is said to have reached a terminal velocity. Increased cross-sectional areas result in an increased amount of air resistance. A skydiver in the spread eagle position encounters more air resistance than a skydiver who assumes the tuck position or who falls feet (or head) first. The greater cross-sectional area of askydiver in the spread eagle position leads to a greater air resistance and a tendency to reach a slower terminal velocity. The importance of cross-sectional area to skydiving is also demonstrated by the use of a parachute. An open parachute increases the cross-sectional area of the falling skydiver and thus increases the amount of air resistance which he encounters (as observed in the animation below). Once the parachute is opened, the air resistance overwhelms the downward force of gravity. The net force and the acceleration on the falling skydiver is upward. An upward net force on a downward falling object would cause that object to slow down. The skydiver thus slows down. As the speed decreases, the amount of air resistance also decreases until once more the skydiver reaches a terminal velocity.

What is gravitational potential energy?

The two examples above illustrate the two forms of potential energy to be discussed in this course - gravitational potential energy and elastic potential energy. Gravitational potential energy is the energy stored in an object as the result of its vertical position or height. The energy is stored as the result of the gravitational attraction of the Earth for the object. The gravitational potential energy of the massive ball of a demolition machine is dependent on two variables - the mass of the ball and the height to which it is raised. There is a direct relation between gravitational potential energy and the mass of an object. More massive objects have greater gravitational potential energy. There is also a direct relation between gravitational potential energy and the height of an object. The higher that an object is elevated, the greater the gravitational potential energy. These relationships are expressed by the following equation: PEgrav = mass • g • height PEgrav = m *• g • h In the above equation, m represents the mass of the object, h represents the height of the object and g represents the gravitational field strength (9.8 N/kg on Earth) - sometimes referred to as the acceleration of gravity. To determine the gravitational potential energy of an object, a zero height position must first be arbitrarily assigned. Typically, the ground is considered to be a position of zero height. But this is merely an arbitrarily assigned position that most people agree upon. Since many of our labs are done on tabletops, it is often customary to assign the tabletop to be the zero height position. Again this is merely arbitrary. If the tabletop is the zero position, then the potential energy of an object is based upon its height relative to the tabletop. For example, a pendulum bob swinging to and from above the tabletop has a potential energy that can be measured based on its height above the tabletop. By measuring the mass of the bob and the height of the bob above the tabletop, the potential energy of the bob can be determined. Since the gravitational potential energy of an object is directly proportional to its height above the zero position, a doubling of the height will result in a doubling of the gravitational potential energy. A tripling of the height will result in a tripling of the gravitational potential energy. -energy stored in raised objects -On Earth we always have the force of gravity acting on us. When we are above the Earth's surface we have potential (stored) energy. This is called gravitational potential energy (GPE). *It all depends on the reference point* ex) an object is on a table, if the reference point is the earth, then in that case the objects gains gravitational potential energy. However, if the reference point is the table, then the object gains no GPE because the table is the reference point, which is always zero*

What is the difference between mass and weight?

Weight is not the same as mass. Mass is a measure of how much matter is in an object. Weight is a force acting on that matter. Mass resists any change in the motion of objects. In physics, the term weight has a specific meaning - which is the force that acts on a mass due to gravity. Weight is measured in newtons. Mass is measured in kilograms. -The mass of a given object is the same everywhere, but its weight can change. We use balances to measure weights and masses. Weight is the result of gravity. The gravitational field strength of Earth is 10 N/kg (ten newtons per kilogram). This means an object with a mass of 1 kg would be attracted towards the centre of Earth by a force of 10 N. We feel forces like this as weight. You would weigh less on the Moon because the gravitational field strength of the Moon is one-sixth of that of Earth (1.6 N/kg). But note that your mass would stay the same. -Mass(m) is a scalar quantity and is measured in kg. The weight of the object is a vector quantity. It is a measure of the force of gravitational attraction on an object in newtons. The mass of an object does not change because the amount of matter the object possesses is constant. However, the weight of an object depends on the acceleration due to gravity, and this value changes, so the weight of an object can change. ex) on the moon, you would weigh less than you do on Earth because gravity is weaker on the Moon. But your mass would be the same because the size and shape of your body haven't change

What is work and energy measured in?

Work done and energy are both measured in joules. This is because work done is equal to energy transferred. A person who has climbed to the top of a flight of stairs has transferred chemical energy stored in their muscles to the gravitational potential energy (GPE) they have when standing at the top. Here the work done (measured in joules) is equal to the GPE transferred (also measured in joules). If that person were to slide down the banisters to the very bottom the GPE would be converted into kinetic energy.

At what stage in an object's fall does the resultant force act downwards?

You said: Just after it starts to fall The resultant force acts downwards on an object just after it starts to fall.

When does a falling object reach terminal velocity?

You said: When the resultant force is zero Correct A falling object reaches terminal velocity when the resultant force is zero. Then the air resistance equals the weight.

For years, space travel was believed to be impossible because there was nothing that rockets could push off of in space in order to provide the propulsion necessary to accelerate. This inability of a rocket to provide propulsion is because ...

a. ... space is void of air so the rockets have nothing to push off of. b. ... gravity is absent in space. c. ... space is void of air and so there is no air resistance in space. d. ... nonsense! Rockets do accelerate in space and have been able to do so for a long time. Answer: D It is a common misconception that rockets are unable to accelerate in space. The fact is that rockets do accelerate. There is indeed nothing for rockets to push off of in space - at least nothing which is external to the rocket. But that's no problem for rockets. Rockets are able to accelerate due to the fact that they burn fuel and push the exhaust gases in a direction opposite the direction which they wish to accelerate.

Many people are familiar with the fact that a rifle recoils when fired. This recoil is the result of action-reaction force pairs. A gunpowder explosion creates hot gases that expand outward allowing the rifle to push forward on the bullet. Consistent with Newton's third law of motion, the bullet pushes backwards upon the rifle. The acceleration of the recoiling rifle is ...

a. greater than the acceleration of the bullet. b. smaller than the acceleration of the bullet. c. the same size as the acceleration of the bullet. Answer: B The force on the rifle equals the force on the bullet. Yet, acceleration depends on both force and mass. The bullet has a greater acceleration due to the fact that it has a smaller mass. Remember: acceleration and mass are inversely proportional.

How do you find acceleration?

acceleration= change in velocity/time interval

Is a force needed to keep an object moving?

saac Newton built on Galileo's thoughts about motion. Newton's first law of motion declares that a force is not needed to keep an object in motion. Slide a book across a table and watch it slide to a rest position. The book in motion on the table top does not come to a rest position because of the absence of a force; rather it is the presence of a force - that force being the force of friction - that brings the book to a rest position. In the absence of a force of friction, the book would continue in motion with the same speed and direction - forever! (Or at least to the end of the table top.) A force is not required to keep a moving book in motion. In actuality, it is a force that brings the book to rest.

What is chemical energy?

stored energy in fuel, foods and batteries -in 1890, a French Chemist Antoine Lavoisier realized that when equal amounts of different substances are burned, the chemical reactions could produce different amounts of heat. ex) when wood burns, the energy in the cellulose molecules is released, turning to heat. This is evidence that there is energy in a chemical reaction, and that this energy can be converted to heat. chemical energy is the potential energy stored in the chemical bonds of compounds. The food you eat contains chemical energy that the body uses to do work in the cells.

If several liquids that don't mix (immiscible) are placed in the same container, what would happen?

the least dense one will rise to the top and the densest one will sink to the bottom. This is also true of gases, but they are often harder to see because gases tend to mix with each other very easily.

While on vacation, Lisa Carr traveled a total distance of 440 miles. Her trip took 8 hours. What was her average speed?

v=d/t = 440 miles/ 8 hr= 55 mi/hr That was easy! Lisa Carr averaged a speed of 55 miles per hour. She may not have been traveling at a constant speed of 55 mi/hr. She undoubtedly, was stopped at some instant in time (perhaps for a bathroom break or for lunch) and she probably was going 65 mi/hr at other instants in time. Yet, she averaged a speed of 55 miles per hour. The above formula represents a shortcut method of determining the average speed of an object.