Physics homework and quiz questions ch 1-7 for final exam
The internal kinetic energy increases 1.5 pt (observed by the increase in the temperature of the heat pack 1 pt) and the internal potential energy decreases 1.5 pt (observed by the liquid becoming gel-like, moving toward a solid state.1 pt), resulting in an overall conservation of internal energy (ΔU=0), which is what you expect for a closed system. 1 pt
(5 points) Consider the heat pack activity we did in class. Explain (in words, not with a diagram) the internal energy changes that occur within the heat pack immediately after it is activated (assume a closed system, before heat is lost). How are these changes observed?
KE equation
1/2mv
Solve for delta t, or change in temp. Which ever has the higher delta t. Q=MCAT
5j of heat is supplied to both a kilogram of water and a kilogram of iron. Which undergoes the greater temp change? Defend your answer. show your work
Yes since it is going im a circle the direction changes No bc inward acceleration
A ball attached to a string is whirled in a horizontal circle such that it moves with a constant speed Does the velocity of the ball change in the process Is the acceleration of the ball equal to zero
The alternating current in the coil will induce an alternating magnetic field around it. The alternating magnetic field around the coil will induce an alternating current in the aluminum or copper. Ohmic heating caused by this induced current will raise the temperature of the aluminum or copper
A coil of wire has a large alternating current flowing in it. A piece of aluminum or copper placed near the coil becomes warm even if it does not touch the coil. Explain why, using the two Principles of Electromagnetism. (Hint: Use the problem-solving process we used for related class demos and for the hot air balloon problem
Pulsed
A little boy lines up a row of dominos each standing on its short end and knocks the first one over with his hand. The result is a wave of dominos all falling one after the other Is this a longitudinal wave of transverse wave Pulsed or continuous
This goes back to Coulomb's Law (F=kq1q2/r2) and the fact that the Electric Force is inversely proportional to distance squared. Since the neutral paper is polarized, the negatively charged rod will be closer to the positive nucleus than it is to the negative electrons. Therefore, the force of attraction between the rod and the nuclei is stronger than the force of repulsion between the rod and the electrons.
A negatively charged rod is brought close to some small pieces of neutral paper. The positive sides of molecules in the paper are attracted to the rod and the negative sides of the molecules are repelled. Since negative and positive sides are equal in number, why don't the attractive and repulsive forces cancel out? (Support your explanation by using the appropriate physics equation)
Higher frequency The clock will run fast (1 point) since the pendulum will complete the number of cycles needed to register one minute in a shorter time
A pendulum clock is taken to a repair shop. It's pendulum is replaced by a shorter one that oscillates with a smaller period than the original Does the shorter pendulum oscillate with a higher or lower frequency What effect if any does this have on how the clock runs? Does it run fast? Slow? The same? Explain using what you learned about how pendulum clocks work.
There is friction between the book and the car and air resistance on the book ---> static friction between book and car, <--- kinteic friction air resistance on the book
A person places a book on the roof of a car and drives off without remembering to remove it. As the book and the car move down a street at a steady speed, two horizontal forces are acting on the book. What are these two forces What are their directions Is one larger than the other or are they equal in magnitude
Higher pitch as its moving towards her Lower pitch as it moves away
A person riding on a moving bus hears the sound from a horn on a car that is stopped. What is different about the sound she hears when the bus is approaching the car compared to when the bus is moving away from the car after passing it?
Greater than bc u are walking into it
A wind is blowing from the north (the air is moving toward the south). When a person is walking toward the north, is the relative speed of the wind that the person senses greater than, the same as, or less than the speed the person senses when not walking?
Force per unit area on inside walls of an inflated object
Absolute pressure
Molecules stop moving
Absolute zero
temperature at which molecules stop moving
Absolute zero is
Ac alternating current step up down changing Dc resistance doesnt change
Ac vs dc
Describes how an objects velocity changes
Acceleration
Determines the loudness of a sound
Amplitude
Describe the distinction between elastic and inelastic collisions. Give an example of each.
An elastic collision is one in which the total KE of the colliding bodies after the collision equals the total KE before the collision. An inelastic collision is one in which the total KE of the colliding bodies after the ollision is not equal to the total total KE before
All objects fall at the same rate, regardless of mass. Galeleo No air resistance on the moon
At the end of the last Apollo 15 moon walk, Commander David Scott performed a live demonstration for the television cameras (we watched a recording of this in class). He held out a hammer and a feather and dropped them at the same time. The result was that the feather and hammer hit the ground at the same time. What principal was demonstrated What scientist was credited with the discovery of this principal Why was this experiment done on the moon and not earth
Final velocity- initial velocity
Change in velocity
A mirror that curves inward and produces an enlarged image
Concave mirror
The water molecules are moving ta the same speed in both glasses because sme temp Greater internal energy in the glass that is full bc it is a full glass. Internal energy is all of the KE and PE of all the atoms and molecules in a substance. There is more water in the full glass which means there is more KE and PE which means more IE More heat will be requires in the full glass because it has twice as much water to increase the temp for
Consider two glasses one filled with water and the other half full, with the water in the two glasses being the same temp. In which glass are the water molecules moving faster? How do you know? In which is there greater internal energy? How do you know? In which will more heat be required to increase the temp by 1 degree celsius? How do you know?
The transfer of heta by bouyant mixing in a fluid
Convection
A mirror that curved outward and produced a reduced image
Convex mirror
The force acting on each of two charges objects is directily proportional to the net charges on the objects and inversly oroportional to the square of the distance between them
Coulombs law
Must be reached for total internal reflection tomoccur
Critical angle
H/mv
De broglie wave length
Guitars, violins, and pianos use vibrating strings to produce sound 1 point. By itself, a vibrating string produces only faint sound because it is too thin to compress and expand the air around it effectively. These instruments employ soundboards to amplify the sound production 1 point. One end of the string is attached to a wooden soundboard, which is made to vibrate by the string. The vibrating soundboard, in turn , produces the sound.
Describe how sound is produced and amplified in string instruments.
The Bohr model accounts for the observed emission line spectra of the elements because when making 'jumps' to smaller orbits, the atom may give up energy in the form of photons whose energies are equal to the differences in the energies of the orbits between which the 'jumps' occur. Since the photon wavelengths are inversely proportional to their energies, the larger the energy differences of the orbits involved in the transitions, the smaller the wavelengths of the photons released. Thus, the spectrum of emitted photons depends on the number and energies of the allowed electron 'jumps' in the atom and, hence, on the structure of the atomic orbits. Since each atom has its own individual set of atomic orbits, each will have its own individual set of emission lines
Describe how the Bohr Model accounts for the production of emission-line spectra from elements like Hydrogen. Why does each element produce its own unique emission-line spectrum?
The photoelectric effect is exhibited by metals when exposed to x-rays, UV light, or (for some metals, including sodium and potassium) high-frequency visible light. By some means, the EM waves give energy to electrons in the metal, and the electrons are ejected from the surface.
Describe the Photoelectric Effect
Sunlight enters the atmosphere and warms the Earth's surface so it (the Earth) emits infrared radiation. Carbon dioxide, water vapor, and other gases in the atmosphere absorb much of this infrared (trapping it) and consequently the atmosphere is warmed
Describe the green house effect
Convection- the transfer of heat by buoyant mixing in a fluid ex: in a boiling pot of water, heated water rises from the bottom to the top of the pot Radiation- the transfer of heat by way of electro magnetic waves ex the sun transfers heat by electromagnetic waves to the earth Conduction- the transfer of heat between atoms and molecules in direct contact ex when you fill a coffee mug with hot coffee. The mug quickly warms up. The coffee and mug are in direct contact
Describe the methods of heat transfer. Give one example of how each is occurring around you at this moment
Brighter light causes more electrons to be ejected each second. Higher-frequency light ejects electrons with higher energy.
Describe the two basic observations/characteristics of the photoelectric effect that were considered "confusing" before Einstein proposed that light itself is quantized.
Occurs when a wave reaches a gap in a barrier
Diffraction
Prrocess of seperating individual wavekengths comprising. A beam of light by shining the light through a prism
Dispersion
A transverse wave is a wave in which the oscillations are perpendicular (transverse) to the direction the wave travels. Examples: waves on a rope, electromagnetic waves. A longitudinal wave is a wave in which the oscillations are along the direction the wave travels. Examples: sound in air, some seismic waves.
Distinguish between a longitudinal wave and a transverse wave. Give an example of each.
When two waves overlap "in-phase" (the peak of one wave matches the peak of another, and valley matches valley), the two waves reinforce each other, and the amplitude is large. This is constructive interference (1 points). When two waves overlap "out of phase" (the peak of one wave matches the valley of the other), the two waves cancel each other. This is called destructive interference.
Distinguish between constructive interference and destructive interference.
Internat energy is the sum of the kinetic energy and potential energies of all the atoms and molecules in a substance Heat is the form of energy that is transferred between two substances because they have different temps
Distinguish between heat and internal energy
Heat is the form of energy that is transferred between two substances because they have different temperatures Temperature is the measurement of how hot or cold something is
Distinguish between heat and temperature
The Doppler Shift is the apparent shift in the frequency of wave fronts emitted by a moving source. With a moving car honking its horn, the frequency of the sound is increased when it is moving toward the observer, and decreased when it is moving away from the observer. The same is true with light, but here instead of sound, the wave fronts emitted by moving stars are light waves. A star moving away from earth would have a lower-shifted frequency and a star moving toward earth would have a higher-shifted frequency. Since blue light has a higher frequency than red light, a "Blue-Shifted Star" would be one that is moving toward Earth and a "Red-Shifted Star" would be one that is moving away from Earth.
Doppler effect Blue shifted vs red shifted stars
Lines of color produced when viewing light from an iluminated gas through a prism
Emission line spectrum
Plancks constant times frequency
Energy of one photon
Occurs when the net force on an object equals zero
Equilibrium
When a balloon is rubbed on a wool sweater, electrons are transferred from the sweater to the balloon. This results in the balloon having an overall net negative charge and the sweater having an overall net positive charge. Since the balloon and the sweater have opposite charges, they will attract.
Explain how a balloon that has been rubbed on a wool sweater will stick to the sweater.
Ferromagnet- metals that are strongly attracted by maggnets, such materials have magnitsm induced in them when they are near a magnet Permanent magnet- metals that retain the magnetism induced in them
Explain the difference between a ferromagnetic and a permanent magnet
A DC power supply, such as a battery, causes a current to flow in a fixed direction in a circuit. The current flows out of the positive terminal of the power supply, moves through the circuit, and flows into the negative terminal of the power supply. If the total resistance in the circuit doesn't change, the size of the current remains constant (as long as the battery doesn't run down). In an AC power supply, the polarity of the two output terminals switches back and forth- the voltage alternates. This causes the current in any circuit connected to the power supply to alternate as well. It flows counterclockwise, then clockwise, then back to counterclockwise, and so on. All the while, the size of the current is increasing, then decreasing, and so forth. AC is used by electric utilities because of the distinct advantage it has over DC: simple, highly efficient devices called transformers can "step up" or "step down" AC voltages. This makes it possible to generate AC at a power plant at some intermediate voltage, step it up to a very high voltage for economical transmission, and then step it down again to lower voltages for use in homes and industries. A flashlight uses a DC current because it is normally battery-operated (in case of power outages) and batteries are a DC power supply
Explain what AC and DC Are. Why is ac used by electric utilities? Why is D.C. Used in flashlights?
The process of refraction (bending of light when entering a transparent medium in which the speed of light changes) was seen by Isaac Newton to be color dependent- the speed of light in any medium is slightly different for each color. The speed of blue light in a prism is lower than the speed of red light in the same prism, so although both rays are bent toward the normal upon passing into the prism, the blue ray is refracted more strongly and emerges from the interface along a different path than the red ray. Sunlight is "white light," which contains all colors of the rainbow. The colors will be dispersed, or separated, as a result of the refraction process because of the wavelength dependence of the speed of light.
Explain what causes the rainbow patterns we see when sunlight passes through a hanging crystal prism. To be complete, you should use "refraction" in your explanation.
Starting from rest on a frictionless floor, you move a 100-kg crate by applying a net force of 50N for a time of 4s. This results in a final speed of 2 m/s after the crate moves a distance of 4m. Find The work done on the crate The final kinetic energy of the crate
F = 50N, d = 4m. W = Fd = (50N)*(4m) = 200J KE= 1/2mv^2 200J= 1/2(100Kg)(2m/s)^2
Since sweat contains a great deal of salt (positive and negative ions), sweat on the skin is a better conductor than dry skin and therefore lowers the resistance of the body. Therefore because current and resistance are inversely proportional due to Ohm's Law, the amount of current that flows in your skin is greater than without perspiration.
For a given consent voltage what happens to the amount of current that flows in your skin when you perspire as compared to when your skin is dry
W=mass times gravity Mass
Formula for weight Is mass or weight constant
Lowest frequencies red Highest violet
Frequencies are perceived as different colors
Measures in hz
Frequency
The number of osscilations per second
Frequency
Objects fall with the same acceleration Feather and bowling ball on moon
Galileo
Nuclear processes
Gamma rays
Energy associated with height
Gravitational potential energy
One cannot specify both the position and the momentum of an electron to arbitrarily high precision. The more precisely you know the position of the electron, the less precisely you can determine its momentum and vice versa. If we let Δx represent the uncertainty in the position of a particle and Δmv represent the uncertainty in the momentum of the particle, then ΔxΔmv ≥ h.
Heisenberg uncertainty principal
Phase change fom liquid to gas Boiling is a process that occurs at the substance's phase change temperature (100˚C for water), while evaporation does NOT occur at the phase change temperature (a water puddle will evaporate even at room temperature).
How are the two processes "boiling" and "evaporating" similar, different
The closer the field lines are together, the stronger the electric field. Arrows placed on the field lines indicate the direction that a positive charge would move if placed in the field at that location. The forces will have equal magnitude but opposite direction. Since F=ma and a proton is much more massive than an electron, the electron will have a much greater acceleration. They will travel in opposite directions.
How do electrical field lines indicate the strength of an electric field? How is the direction of an electric field indicated with electrical field lines? If you place a free electron and a free proton in the same electric field, how will the forces acting on them compare? How will their accelerations compare? Their directions of travel?
Loude sounds have larger amplitudes Frequenct affects the pitch Higher frequency, highe pitch Waves with higher frequencies have shorter wave lengths. Inversely propotional. V=f lambda Frequency is the number of cycles of a wave passing a point per unit time. The amplitude is the height of those waves. There is no relationship between the two. Amplitude isnhow loud or sodt something is. If you increase the frequency only the pitch changes it becomes hightpwr that doesnt change how loud or soft the sound is
How does changing the amplitude of a sound wave affect the sound heard? How does changing the frequency of a sound wave affect the sound heard? What is the relationship between frequency and wave length? Give an equation What is the relationship between amplitude and frequency?
When you jump, you put a force downward on the floor (2 points). Newton's 3rd Law (1 point) states that the floor will put an equal and opposite force on you (2 points), and that force accelerates you upward (1 point). 1 point for effort. Gravity does always act on you, but it is NOT part of the 3rd Law "pair of forces" at work when you jump, especially since gravity pulls you down and jumping involves moving up.
How is Newton's 3rd Law of Motion involved when you jump straight upward? (Hint: The "landing" of the jump is not relevant here.) Be specific about which forces are involved in your explanation.
A bat emits a short burst of sound that reflects off surrounding objects such as the ground, trees, and flying insects. The bat detects these echoes and uses the time it takes the sound to make the round-trip to determine the distances to the objects.
How is echolocation used by bats when hunting prey
Doppler Radar uses a combination of echolocation and the Doppler effect. The time between transmission and reception gives the distance to the object, whereas the amount of frequency shift is used to determine the speed. If the frequency shift is higher (when car moves toward radar gun) or lower (when car moves away from radar gun) than the expected shift of a car moving at the speed limit, then the officer knows the car is speeding.
How is the Doppler effect used by the police
In a gas with a density that is low enough that interactions between its constituent particles can be ignored the pressure volume and temp of the gas r related pv=nRT
Ideal gas law
Like Gravity, the Electric Force is inversely proportional to distance squared. So if the proton is three times farther away, the force will decrease by 1/(32) = 1/9. If it is 5 times farther away, the force will decrease by 1/(52) = 1/25.
If a proton at a particular distance from a charged particle is repelled with a given force, by how much will the force decrease when the proton is three times farther away from the particle? When it is five times farther away?
Greater
If an abject floats on top of a body of water than the density of the object is what compared to the density of the water
Consider what would happen if the acceleration due to gravity on earth (normally 9.8 m/s2) suddenly doubled. How would that affect atmospheric pressure? How would it affect the pressure at the bottom of a swimming pool? Explain your answers, using what you know from part a.
If g doubled, then the weight of everything would double, including air and water molecules (W=mg). Since this is the force that causes pressure (P=F/A=W/A), the pressure everywhere would double. This includes both atmospheric pressure and the pressure at the bottom of a swimming pool.
4 times the centripical acceleration
If two identical cars go around the same curve and one is going twice as fast as the other than the faster car has blank. Recall the formula for centripetal acceleration a=v^2/r
Use table 4.4 in your book to answer the following question. The mass density of a mixture of ethyl alcohol and water is 950 kg/m3. Is the mixture mostly water, mostly alcohol, or about half and half? What is your reasoning According to table 4.4, the mass density of ethyl alcohol is 791 kg/m3 and the mass density of water is 1,000 kg/m3.
If we assume a volume of 2m3, a half and half mixture would have a mass of 791kg + 1,000kg = 1791kg. The density of the half and half mixture would be D=m/V = 1791kg/2m3 = 895.5 kg/m3. The mixture in this problem is given as 950 kg/m3, so I would conclude that it contains mostly water, since the density is higher than a half and half mixture.
How do solids, liquids, and gases differ from one another in terms of the forces between their atoms and molecules
In solids, attractive forces between particles are very strong; the atoms or molecules are rigidly bound to their neighbors and can only vibrate. In liquids, the particles are bound together, though not rigidly; each atom or molecule can move about relative to the others but is always in contact with other atoms or molecules. In gases, the attractive forces between particles are too weak to bind them together; atoms or molecules move about freely with high speed and are widely separated; particles are in contact only briefly when they collide.
B
In which of the following is work being done by the person on the given object A person holds a book at a constant height and walks horizontally A person pulls a wagon by its handle and the wagon moved horizontally A person swings a ball attached to a string in a circular motion A person pushes on the floor with his or her feet and constantly jumps
Kinetic energy is not conserved
Inelastic collision
The property of matter that makes it resist acceleration
Inertia
Heat radiation and communication om a shorter scale ex remote
Infared radiation
The process by which two waves produce alternating regions of larger amplitude and zero amplitude waves
Interference
Measurement of energy
Joules
Energy associated with motion
Kinetic energy
Occurs between objects that move relative to eachother
Kinetic friction
An ice skater has a rotational inertia of 1.2 kg*m/s2 when her arms are extended and a rotational inertia of 0.5 kg*m/s2 when her arms are pulled in close to her body. If she goes into a spin with her arms extended and has an initial rotational velocity of 1 revolution/second, what is her rotational velocity when she pulls her arms in close to her body? (Hint: Use Conservation of Angular Momentum)
L=IW Angular momentum= rotational inertia x Spinrate (1.2)x(1)=(.5)xW Solve
The total linear momentum of an isolated system is constant
Law of conservation
The angle of incidence equals the angle of reflection
Law of reflection
A light ray is bent toward the normal when it enters a transparent medium in which light travels more slowly. It is bent away from the normal when it enters a medium in which light travels faster.
Law of refraction
Squiggly 1/ r^2
Law of universal gravitation
Used for communication ove short distance ex wifi
Microwaves
Mass times velocity
Momentum
Scanningg elements
Name one device that makes use of the photo electric effect
Universal law of gravitation- showed that the force that makes apples fall from tres is the same force keeping the planets pin orbit An object will remain at rest or in uniform motion with a constant velocity unless acted on by a net external force F=ma When one object exerts a force on a scond object the second object exerts an equal and op force on the first
Newton and his laws
An object will remain at rest in uniform motion with a constant velocity unless acted upon by a net extrenal force F=ma Fbona=-faonb
Newtons laws
I=v/r
Ohms law
Pressure equation
P=F/A
A crate with a mass of 100kg is lifted onto a loading dock 2m above ground level. How much potential energy has been gained?
PE = mgh = (100kg)(9.8 m/s2)(2m) = 1960 J
Pressure, volume, temp
PV=nRT what does the letters stand for
What is Pascal's principle? How is Pascal's principle involved in a car's brake system? How is this USEFUL? In other words, why don't we just attach the brake pedal directly to the brake pad?
Pascal's Principle: "Pressure applied to an enclosed fluid is transmitted undiminished tl all parts of the fluid and to the walls of the container." When the brake pedal is pushed, the pressure in the brake fluid is increased. This higher pressure is passed on through the brake lines and pushes the pistons in the wheel cylinders outward, thereby applying the brakes The brake system USES Pascal's principle by making the area of the wheel cylinder greater than the area of the master cylinder. Since the pressure is transmitted (is the same) throughout the fluid, and Pressure = Force/Area, there is a greater force on the wheel cylinder Without this greater force, we might as well attach the brake pedal directly to the brake pad.
When boarding an airplane, you bring a bag of chips and, while you are in flight, you notice that the bag puffs up. Explain how this happens by answering the following questions: a. When the bag is packaged and sealed on the ground, the pressure inside the bag (Pbag) is equal to normal atmospheric pressure (Pnormal atm). As the bag is sealed, no more air molecules will enter or leave the bag. When the bag ascends up into the sky inside the plane, does Pbag increase, decrease, or stay the same? b. When the bag boards the plane, the plane's cabin pressure (Pcabin) is equal to Pnormal atm. What is the GAUGE pressure (difference between pressure inside and outside the bag? c. As the plane ascends, does Pcabin increase, decrease, or stay the same? d. How does the gauge pressure change as the plane ascends? e. Why does the bag puff up?
Pbag will stay the same. Since the number of molecules inside the bag doesn't change, the number of molecules putting forces on the inside walls of the chip bag (which results in the pressure inside of the bag) will be the same. At ground level, the pressure in the bag Pbag is equal to the air pressure inside the cabin Pcabin. Since GAUGE pressure is Pabs - Patm, or Pinside bag - Poutside bag, or Pinside bag - Pcabin the gauge pressure is zero. As the plane ascends, the air becomes slightly thinner and Pcabin decreases. The cabin is pressurized in order to stabilize around the 14.7 psi we are used to on the ground. The cabin pressure would definitely be greater than the air pressure outside of the plane because of this. However, the air pressure still does drop slightly inside. We know this because our ears still pop! Gauge pressure is still Pinside bag - Pcabin, but the two are no longer equal. As the cabin pressure decreases, the gauge pressure will increase Because the gauge pressure is no longer zero and the pressure inside the bag is greater than the pressure outside of the bag, the bag puffs up. Even though the pressure inside the bag never changed
Time required for one full cycle of a repeating orocess
Period
Trransveerse waaves with a perffered directin of oscilation
Polarized light
Measure in jouls per second
Power
P=f/a
Pressure definition
Used for communication over long distance ex radio, tv
Radio waves
Rotational analogue to mass
Rotational inertia
Restoring force
Simple harmonic motion is the result of a
Describe how the four phases of matter differ from one another in terms of their observable properties.
Solids are rigid; they retain their shape unless distorted by a force. Liquids flow readily; conform to the shape of a container; have a well-defined boundary (surface). Gases flow readily; conform to the shape of a container; do not have a well-defined surface; can be readily compressed. Plasmas have the properties of gases but also conduct electricity.
Wave form
Sound tone quality is determined by its
Heat needed to raise the temp of 1kg of a substance by 1 degree celcius
Specific heat capacity
Occurs when light strikes a very smooth shiny surface
Speculation reflection
occurs between objects not moving relative to each other
Static friction
Mars bars ^2 Marsbars/zots Marsbars/zots
Suppose critters are discovered on mars who measure distance in mars bars and time in zots What would the units of area be in this system What would the units of speed be in the system What would the units of acceleration be in this system
Proportional tot he average kinetic energy of particles in a substance
Temp
It is said that a gas fills all the space available to it. Why, then, doesn't the atmosphere go off into space?
The atmosphere consists of gas particles, which themselves have mass. These particles are held to the Earth by the gravitational force that acts on all things that have mass.
Consider two people walking in deep snow, one wearing snowshoes, the other wearing regular boots. If both people have the same weight, do they also put the same force on the snow? If not, which one puts more force on the snow? Which shoe has a greater area? Which shoe puts a greater pressure on the snow? Consider here the equation for pressure. Which shoe will prevent the person from sinking deep into the snow, thereby making it easier to walk?
The force on the snow EQUALS the weight of the person. Therefore, they put EQUAL forces on the snow snow shoe With an equal force applied, the shoe with the smaller area (regular boot) will put a greater pressure on the snow. In other words, the force is more "concentrated" with a boot and more "spread out" with a snoeshoe. The showshoe, by putting less pressure on the snow, will be less likely to make the person sink into the snow.
What is the force that causes atmospheric pressure? What is the force that causes pressure at the bottom of a swimming pool?
The force that causes atmospheric pressure is the weight of the air molecules. Pressure at the bottom of a pool is caused by the weight of the water in the pool plus the weight of the air molecules extending in a column above it.
How can the gravitational potential energy of something be negative?
The gravitational potential energy of an object is negative when the object is below the chosen reference level ("zero"). A ball in a hole with the level ground above it as the reference level is one example.
Due to Newton's 3rd Law, the electron will attract the proton with exactly the same amount (magnitude) of force that the proton attracts the electron
The proton that is the nucleus of the hydrogen atom attracts the electron that orbits it. Relative to this force, does the electron attract the proton with less force, with more force, or with the same amount of force?
A pudddle of oil in a parking lot shows swirls of rainbow colors
Thin film interference
A moving electric charge (current) produces a magnetic field in the space around it A magnetic field (b) exerts a force on a moving electric charge A moving magnet produces an electric field in the space around it
Three basic interactions between electricity and magnetism
Rotational analogue to force
Torque
Osscilations are perpendicular to the direction the waves travel
Transverse waves
Used to see bodily fluid at a chrime scene, tanning beds
Ultraviolet radiation
PV=nRT The pressure is constant. The pressure on the outside is the same as the pressure on the inside of the balloon b/c there is a hole in the bottom. If the pressure is constant rhan the temp and volume are propotional. If temp increases than volume increases. We know the temp is increasing bc it is getting higher. If the volume increases than density decreases. The mass doesnt change there are no molecules or atoms added or lost in the balloon. The fire isnt an air pump. Its not adding air to the balloon. Bc the gas inside the balloon is lees dense than the air outside the balloon it rises
Using the ideal gas law and the equation for mass density explain how a hot air balloon rises
Each wave front expands outward from the point where the source was when it emitted that wave front. As the bus approaches the car, the wavefronts are bunched together, resulting in a lower wavelength and therefore higher frequency. As the bus moves away from the car, the wave fronts are spread out, resulting in a longer wavelength and therefore lower frequency
Using this scenario as an illustration, explain how the Doppler Effect works. You may wish to draw a picture to support your explanation. You must relate what you wrote in part a to what you wrote in part b.
Describes an objects speed with direction soecified
Velocity
Colors, detected by human beings
Visible light
equation for weight
W=DF
A crate is pulled a distance of 4m across the floor under the influence of a 50N force applied by a rope to the crate. What is the work done on the crate by the 50N force if The rope is horizontal, parallel to the floor? The rope pulls at an angle to the floor, so that the horizontal component of the 50N force is 30N?
W=FD W=50Nx4m W=FD W=30Nx4m
V=lambda times f
Wave speed
Two cranes start lifting identical steel beams at the same time, and stop lifting at the same time. One crane is putting out twice as much power as the other. Assuming friction is negligible, what can you conclude is happening to explain this difference? Include any relevant equations in your answer.
We can define Power as Energy/time, or (since Work done = Energy transferred), Power is Work/time. The problem says the two cranes are lifting the same weight at the same time, while one crane is putting out twice the power as the other. This means that one is doing twice as much work (force time distance in the vertical direction), and since the force to lift an identical beam would be the same, the more "powerful" one must be lifting the beam twice as high, giving its steel beam twice as much potential energy as the other
Distance time mass
What are the basic or fundamental physical qualities
Electrons move about the nucleus of an atom in well-defined circular orbits much like the orbits of planets about the sun. The electron orbits are quantized—each orbit has a well-defined energy and angular momentum associated with it, such that the larger the orbit, the greater the energy. Electrons do not radiate energy (emit light) while in one of these stable orbits. (iii) Electrons may make transitions between the allowed orbits. Transitions to larger orbits require that the electrons gain energy, while transitions to smaller orbits require that they lose energy.
What are the three basic assumptions of the Bohr Model?
Heat flows from reagions of high energy to regions of low energies. Hot to cold
What determines the direction of heat flow
The energy of an object or a system is 'quantized' if it can take on only a certain set of prescribed, discrete values instead of ones which are continuously distributed. In a quantized system, energy is available only in individual chunks having certain sizes, not in any arbitrary amount or quantity
What does it mean when we say that the energy of something is "quantized"?
Such materials have magnitism induced in them when they are near a magnet
What happens to a ferry material when it is placed in a magnetic field
When waves are reflected from a concave reflecting surface, the waves converge toward each other and are focused at one point where the amplitude of the wave increases2 points . Satellite receiving dishes detect radio waves that are sent over long distances. The radio waves are reflected, focused, and amplified at the point where a receiver is placed to pick up the signal so it can then be transmitted to our radios/televisions
What happens to a wave when it encounters a concave reflecting surface? How is this useful in terms of radio/television broadcasting via satellite dishes
A particle or quantum of electromagnetic radiation The energy of a photon is directly related to its frequency Inversly proportional
What is a photon How is its energy related to frequency How is its energy related to its wavelength
When a wave passes through nearby gaps in a barrier, they will diffract (or spread out)
What is diffraction
Echolocation is the process of using the waves reflected from an object to determine its location
What is echolocation
Interference occurs when two waves, usually of equal frequency and amplitude, arrive at the same place at the same time.
What is interference
The apparent change in frequency of a wave fronts emmitted by a moving source
What is the Doppler effect
The pressure at any point in a fluid is determined by the weight of the fluid above.
What is the law of fluid pressure
The purpose of fuses is to stop the flow of dangerously high currents through electronics that could be damaged. When the current gets too high within a circuit, a fuse will break, and the current will no longer flow through the circuit. Fuses must be connected in SERIES in the circuit to be effective. If they were connected in parallel, the dangerously high current would continue to flow through electronics unaffected.
What is the purpose of having fuses or circuit breakers in electric circuits? How should they be connected in circuits so they will be effective
Because the problem states that the proton is repelled, and we know that a proton has a positive charge and like charges repel, we can conclude that the unknown particle has a positive charge.
What is the sign of charge of the particles in this case how do you know
E=hf
What is thee energy of a single photon of light
Protons, positive electrons, neg All electrons have identical neg charges. Electron charge is equal and opp to proton charge There is an equal number of protons and electrons Neutral or 0 If an atom loses an electron, it is left with an overall positive charge and is said to be a "positive ion." If an atom gains an electron, it is left with an overall negative charge and is said to be a "negative ion."
What part of an atom is positively charged, negatively charged How does the charge of one electron compare to that of another electron? How does it compare with the charge of a proton? How do the numbers of protons in the atomic nucleus normally compare to the number of electrons that orbit the nucleus What is normally the net charge of an atom What is a positive ion, a neg ion
Liquids expand faster than solids. If both the liquid and solid glass would expand at the same rate you wouldnt get an accurate temp.
When a mercury thermometer is heated the mercury expands and rises in the thin tube of glass. What does this indicate about the relative rates of expansion for mercury and glass? What would happen if their expansion rates were the same?
Interference occurs when two waves, usually of equal frequency and amplitude, arrive at the same place at the same time. When a wave passes through nearby gaps in a barrier, they will diffract (or spread out), and can therefore overlap and interfere. If the waves passed straight through the gaps without spreading out (diffracting), the two emerging waves will never overlap and therefore cannot interfere.
When a wave passes through two nearby gaps in a barrier, interference will occur, provided that there is also diffraction. Why must there be diffraction in order for interference to occur?
Speed
Which if the following is not a vector Velocity Acceleration Force Speed
C
Which of the following is correct Energy is conserved in the absence of an external force Momentum is conserved in the absence of external work Angular momentum is conserved in the absence of external torque A free falling body experiences no external force
Inertia
Which of the following is not a force Friction Gravity Weight Inertia
Our ears respond to changes in pressure
Why are we able to hear
When a note is played on a string instrument, the wave pulse travels back and forth on the string, being reflected each time at the ends. This makes the soundboard vibrate at a frequency equal to the frequency of the pulse's back-and-forth motion. The frequency of the pulse's motion depends on the speed of the waves on the string and on the length of the string. When a string is tightened, the wave speed is increased. The pulse moves faster on the string and makes more round-trips each second, resulting in a higher frequency of the sound produced.
Why does tightening a string change the frequency of the sound it makes? Your explanation should include a statement about wave speed (as we saw in the in-class long rope demonstration).
Another way to say it would be that because the sweat particles with the highest kinetic energies are the ones able to "escape" and evaporate, it leaves the rest of the sweat still on the body with a lower average internal kinetic energy, meaning a lower temperature.
Why is sweating an efficient mechanism for cooling off on a hot day?
Allows you to see bones
Xrays
Could the linear momentum of a turtle be greater than the linear momentum of a horse? Explain why or why not.
Yes. Linear momentum is mass times velocity. If the horse is not moving, its linear momentum is zero. The linear momentum of ANY velocity would be greater than zero.
Conservation law
a law that states the total amount of a certain physical quality present in a system stays constan (is conserved)
absolute vs guage pressure
actual pressure in a tire the pressure relative to the outside air
fluid
any substance that flows regularly
matter
anything that has amtter and occupies space
Weight of the displaced fluid
bouyant force
equation for distance
d=1/2at
Law of conservation
energy cannot be created ordestroyed, only converted from one form to another
macroscopic vs microscopic
external form and properties of matter internal
Use the conservation of momentum law to find the speed of granny and ambrose together after collision.
initial momentum of granny x initial speed of granny plus the initial momentum x speed of ambrose = mass of granny plus mass of ambrosexV Solve for V MV+MV=(m+m)V
A pendulum bob with a mass of 0.50kg is released from a position in which the bob is 12cm above the low point in its swing. What is the speed of the bob as it passes through the lowest point in its swing? (Hint: Use Conservation of Energy and the equations for Potential and Kinetic Energy)
m = 0.5 kg, h = 12cm = 0.12m, v = ? at the low point. The initial energy is E = PE = mgh = (0.5 kg)*(9.8 m/s2)*(0.12m) = 0.588 J At the low point, the potential energy is zero, so: E = KE = 0.588 J 1/2mv2 = 0.588 J Dividing both sides by 1/2m: V2 = KE/(1/2m) = (0.588 J)/(1/2)(0.5 kg) = 2.35 m2/s2 Taking the square root of both sides: v = 1.53 m/s
equation for momentum
massxspeed=momentum
PE equation
mgh
V=IR
ohms law equation
archimedes principal
the bouyant force acting on a substance in a fluid at rest is equal to the weight of that fluid displaced by the substance
Pressure
the force pre unit area when the force acts perpendicular to a surface
work
the force that acts times the distance moved in the direction of the force
law of fluid pressure
the guage pressure at any dept in a fluid at rest equals the weight of the fluid in a column extending from that depth to the top of the fluid divided by the cross sectional area of the column
Linear momentum
the mass of an object times its velocity F=change in momentum/change in time
mass density
the mass per unit volume of a substance
energy
the measure of a systems capacity to do work. that which is transferred when work is done
power
the rate of doing work. the rate at which eneryg is transferred or transformed
torque
the rotational analogue of force t=fxr r is the distance between the pivot point and where the force is applied
angular momentum
the total angular momentum of an isolated system is constant
buoyant force
the upward force exerted by a fluid on a substance partly or completely immersed in it