Physics: Power/Energy/Work Last Concepts

motion of particles. energy results in an object or a system having a temp that can be measured. can be transferred from one object or system to another in the form of heat

thermal energy

state at which 2 objects in contact gain the same temperature; there is an equal rate of energy flow between them

thermal equilibrium

What happens to the kinetic energy of a moving object when the net work done is positive a. KE increases b. KE decreases c. KE is the same d. KE is 0 e. KE is negative

A

What is the best way to increase power? a. increase the amount of work done in a given amount of time, or do a given amount of work in less time b. increase the amount of work done in a given amount of time, or do a given amount of work in more time c. decrease the amount of work done in a given amount of time, or do a given aount of work in less time d. decrease the aount of work done in a given amount of time, or doa given amount of work in more time

A

a force acting on an object does no work if: a. force is greater than force of friction b. force is not in the direction of the object's motion answern is b c. machine is used to move the object d. object accelrates

A

An object is thrown straight down, which of the following is true about the sign of the work done by the gravitational force while the object moves up then down: a. work is positive on way up, positive on way down b. negative way up, negative d. negative, positive d. positive, negative e. zero, zero

C

Liz throws a softball with a force of 63 N and a distance of 25 m. Jamie throws the softball with the same amount of force, but the ball only goes 17 m. Which girl did less work a. same work b. liz c. jamie d. no work

C

The law of conservation explains that while work is greater than work output for all machines, the missing energy must have been: a. miscalculated b. converted into something ike friction ANSWER IS B c. convreted back into input energy d. lost

D

True or False: A force acting perpendicular to an object's displacement does negative work

Fallse

True or False: The harder you push on a wall, the more work you do.

False

True or False: When mechanical energy is conserved, the kinetic energy you end up with always equals the gravitational potential energy that you start with F

False

A truck driver is trying to push a loaded truck but the truck stays stationary. Is work done?

No, zero work done

So when the car rolls down a hill from an elevated position, what does ME transfer to?

PE to KE

True or False: A force acting in the direction of an object that it is moving alway does positive work.

True

True or False: The force needed to lift an object at a constant speed is equal to the weight of an object:

True

How is power related to work? How can you increase the amount of power?

Work done is a measure of the energy transferred when a force moves a load, power is the rate of energy transfer, time,

How do you increase the amount of work you do?

apply a force

How do you accelerate an object?

apply a force, requires work to be done

When does the kinetic energy of a roller coaster increase the most?

bottom of roller coaster

device used to measure changes in themal energy

calorimeter

transfer of KE when particles collide

conduction

What are three methods of heat transfer?

conduction, convection, raditation

What does it mean to be conserved? When is mechanical energy not conserved?

conservation of mechanical energy states that the total mechanical energy in a system (i.e., the sum of the potential plus kinetic energies) remains constant as long as the only forces acting are conservative forces. Kinetic energy is not conserved by these non-conservative forces occurring during the collision

motion of fluids or gases caused by the temperature differences

convection

When jumping from a higher height into sand, will the hole you make be deeper or shallower compared to the hole when jumping from a lower height?

deeper, higher height= more PE, more PE gets changed into KE so more KE when reaching ground

What type of energy is this example: rubber band, bungee cord

elastic potential energy

energy stored as a result of applying a force to deform an elastic object. energy is stored until the force is removed ad the object springs back to its original shape; compressing, stretching, twist

elastic potential energy

ability to do work

energy

Why does following through make a hit ball go faster?

following through increases the distance you push the ball, more work, more KE= more velocity

What type of energy is this: book on shelf, roller coaster at the top of the ride

gravitational potential

: type of stored energy associated with the position of an object in a gravitational field

gravitational potential energy

Is a higher specific heat harder or easier to change?

harder

energy that flows between two objects as a result of different in temperature Unit: Joule, Q

heat

form of energy that can be transferred from one object to another or even created at the expense of the loss of other forms of energy defined as energy in transit from a high temperature object to a lower temperature object.

heat

What does heat lost by hot object equal?

heat gained by cold object

What does Q stand for? in Joules What does C stand for? in J/kgC What does m stand for? in kg What does T stand for? in C or K

heat gained/loss, specific heat of substance, mass, change in temperature

What is Q, C, m, and t?

heat gained/lost, specific heat, mass, temperature

(symbol: Q) is energy. It is the total amount of energy (both kinetic and potential) possessed by the molecules in a piece of matter. Heat is measured in Joules.

heat, When you heat a substance, either of two things can happen: the temperature of the substance can rise or the state of substance can change. Comparison chart Heat versus Temperature comparison chart Edit this comparison chart Heat Temperature Definition Heat is energy that is transferred from one body to another as the result of a difference in temperature. Temperature is a measure of hotness or coldness expressed in terms of any of several arbitrary scales like Celsius and Fahrenheit. Unit Joules Kelvin, Celsius or Fahrenheit Symbol Q T SI unit Joule Kelvin Particles Heat is a measure of how many atoms there are in a substance multiplied by how much energy each atom possesses. Temperature is related to how fast the atoms within a substance are moving. The 'temperature' of an object is like the water level - it determines the direction in which 'heat' will flow. Ability to do work Heat has the ability to do work. Temperature can only be used to measure the degree of heat.

What does gravitational potential energy depend on?

height

When jumping from a higher height, do you reach the ground at a faster or slower rate than jump from a lower height?

higher height= PE, connected into KE as you fall so higher person ends with more KE more KE= faster

Where does a pendulum have the most potential energy? The most kinetic energy?

highest, lowest

Potential Energy or Kinetic Energy: Rollercoaster going down a hill Women swings a golf club

kinetic

What is thermal energy an example of?

kinetic energy

energy associated with motion; can be transferred between objects and transformed into other chunks of energy ex. squirrel collide with stationary chipmunk, after collision, some initial kinetic energy of squirrel has been transferred into the chipmunk or transformed to some other form of energy

kinetic energy

energy of motion; cheetah running, sprinter

kinetic energy

energy cannot be created or destroyed

law of conservation of energy

What does thermal equilibrium depend on in terms of final temperature factors?

mass, specific heat

What typeof energy is this: riding a bike, rowing a boat

mechanical

What is meant by thermal equilibrium?

no net flow of heat, condition under which two substances in physical contact with each other exchange no heat energy observed that a higher temperature object which is in contact with a lower temperature object will transfer heat to the lower temperature object. The objects will approach the same temperature, and in the absence of loss to other objects, they will then maintain a constant temperature. two objects are at the same temperature. Two objects in physical contact with each other are in thermal equilibrium when they reach the same temperature and an exchange of heat energy no longer occurs. According to HyperPhysics, the relation of thermal equilibrium follows the Zeroth Law of Thermodynamics, which states that "if two systems are at the same time in thermal equilibrium with a third system, they are in thermal equilibrium with each other." CONTINUE READING KEEP LEARNING What is countercurrent heat exchange? What is Wien's displacement law? What is the difference between heat and temperature? FULL ANSWER When a hotter object is placed in contact with a cooler object, the hotter object transfers heat energy to the cooler object. This process causes the hotter object to cool and the cooler object to become warmer. This exchange of energy continues until the two objects have the same temperature or are in a state of equilibrium. To illustrate this, take for example a cup of hot water (system A) and a cup of cold water (system B) that are left in a room (surroundings). The process that occurs between the cup of hot water (system A) and the room (surroundings) is exothermic because heat energy is lost. Conversely, the process that occurs between the cup of cold water (system B) and the room (surroundings) is endothermic because heat energy is absorbed by the cup of cold water. Eventually, all three reach the same temperature, the temperature of the room. It is important to note that whenever two objects of different temperatures are placed in contact with each other, energy from warmer objects always moves to the cooler objects. In this respect, the direction of energy transfer does not depend on the amount of energy, only the temperatures involved.

energy stored; book on shelf; energy that is stored as a result of position or height; energy acquired by it by the virtue of its position and an energy which is readily available for use ex. Person on sled on top of hill ex. steel dam holding back a rsesoviour of wate

potential energy

rate at which work is done

power

How is KE related to mass and velocity?

proportional, Kinetic energy is dependent on the object's mass and velocity. Since kinetic energy is the energy of motion, all objects that have motion have potential kinetic energy. This energy is determined by the size of the object, where the object is and the speed or velocity it is moving at. CONTINUE READING KEEP LEARNING What is the formula to calculate kinetic energy? What is dictated by the mass and velocity of an object? What is Wien's displacement law? FULL ANSWER Kinetic energy is directly proportional to the square of its velocity or speed. If an object has a speed of two squared, then the kinetic energy will have a twofold increase with a factor of four. A good example of kinetic energy is holding two magnets apart. When held apart, they have the potential to be released and moved together, doing work in the process of moving. If a person is standing at the top of a building, they have more potential energy than if they were standing on the sidewalk below it. This is because gravity could pull that person or object down. When this occurs, the gravity is doing work on the object. The speed at which the object falls or the magnets move are directly related to their mass. Bigger objects will fall faster and larger heavier magnets will move towards each other more slowly than smaller magnets would if the magnetic charge was the same.

transfer of energy by electromagnetic waves

radiation

energy required to change the temperature of 1 kg of a substance by 1 degree Celsius Unit: J/kgK

specific heat capacity

KE depends on velocity of an object _________; velocity of object doubles, KE quadruples For given mass, what is KE directly proportional to?

squared, velocity, any given velocity KE of an object is directly proportional to its mass

(symbol: T) is not energy. It relates to the average (kinetic) energy of microscopic motions of a single particle in the system per degree of freedom. It is measured in Kelvin (K), Celsius (C) or Fahrenheit (F).

temperature

measure of the ability of a substance, or more generally of any physical system, to transfer heat energy to another physical system.

temperature

After work is done, energy has been ____________ to object-object will move with new constant speed. Energy transferred is KE and depends on _________/_______

transferred, mass/speed

Mrs. Scholma pushed Mr. Scholma's desk from his old classroom to his new one during the summer. Did she do work?

yes, pushed horizontally/distance was horizontally, work done

Is Work Done: Yes or No Lifting a Book pushing a shopping cart pushing on a wall carrying a book to your desk kicking a ball holding weights over your head

yes, yes, yes, no, no, no