CP1 Exam 3
A 10 g rubber ball and a 10 g clay ball are each thrown at a wall with equal speed. The rubber ball bounces and the clay ball sticks. Which ball receives the greater impulse from the wall? a. The clay ball because it sticks b. The rubber ball because it bounces c. They receive the same impulse because they have the same momentum d. Neither receives an impulse because the wall doesn't move
B
A beam with a pivot on the left end is suspended from a rope. In which direction is the force of the pivot on the beam? a. Right horizontal arrow b. Up arrow c. Up-Right diagonal arrow d. Down arrow e. Down-Right diagonal arrow
B
A block with an initial kinetic energy of 4.0 J comes to rest after sliding 1.0 m. How far would the block slide if it had 8.0 J of initial kinetic energy? a. 1.4 m b. 2.0 m c. 3.0 m d. 4.0 m
B
A child is on a playground swing, motionless at the highest point of his arc. What energy transformation takes place as he swings back down to the lowest point of his motion? a. K -> Ug b. Ug -> K c. Eth -> K d. Ug -> Eth e. K -> Eth
B
A large -20C ice cube is dropped into a super-insulated container holding a small amount of 5 C water, then the container is sealed. Ten minutes later, the temperature of the ice (and any water that has melted from the ice) will be warmer than -20C. This is a consequence of a. The first law of thermodynamics b. The second law of thermodynamics c. The third law of thermodynamics d. Both the first and the second laws e. Joule's law
B
A light plastic cart and a heavy steel cart are both pushed with the same force for 1.0 s, starting from rest. After the force is removed, the momentum of the light plastic cart is ________ that of the heavy steel cart a. Greater than b. Equal to c. Less than d. Can't say, it depends on how big the force is
B
A light plastic cart and a heavy steel cart are both pushed with the same force for a distance of 1.0 m, starting from rest. After the force is removed, the kinetic energy of the light plastic cart is ________ that of the heavy steel cart. a. Greater than b. Equal to c. Less than d. Can't say, it depends on how big the force is
B
Absolute zero is a. The temperature at which water freezes b. The point at which the kinetic energy of the atoms is zero c. Not real. It only exists in science fiction d. Different for different temperature scales
B
An example of conservation of angular momentum is a. A car going around a corner b. An ice skater changing the speed of a spin c. A golf club hitting a golf ball d. Jumping off a diving board
B
Do explosions conserve momentum? a. Only for rockets b. Yes, because all forces are internal to the system c. Only if the original object is stationary d. No, because objects can go from stationary to moving
B
How is specific power defined? a. Power of transfer times the duration of the transfer (Δt) b. Power of the transfer divided by the mass of the object causing the transfer c. Mass of the object causing the transfer divided by the duration of the transfer d. Mass of object causing the transfer multiplied by the power of the transfer
B
In a perfectly elastic collision a. The final momentum cannot be determined b. Momentum is always conserved c. None of these are correct d. Momentum is conserved only if all objects in the interaction have the same mass
B
In order for an object to be in static equilibrium a. Either the net force or the net torque equal zero b. Both the net force and the net torque equal zero c. The new torque equals zero d. The new force equals zero
B
Living things do not violate the 2nd law of thermodynamics because a. They do not experience a change of entropy b. They are not an isolated system c. They are not subject to the 2nd law of thermodynamics d. All of these are true
B
Living things don't violate the 2nd law of thermodynamics because a. They are not isolated from the environment b. All of these are correct c. They take in energy d. They radiate heat
B
Rank in order, from greatest to least, the kinetic energies of each sliding puck a. B > D > A > C b. B > D > A = C c. D > B > A > C d. D > B > A = C
B
The 2nd law of thermodynamics says a. Nothing about entropy b. Total entropy never decreases c. The entropy of an isolated system always decreases d. Total entropy can decrease for certain processes
B
The conservation of energy equation must include a. Thermal energy leaving the system b. All of these are correct c. Thermal energy added to the system d. Work done by the system. e. Work done on the system
B
The efficiency of a heat engine a. Is always 100% b. Is never 100% c. Cannot be determined d. Is usually 100%
B
The end of a spring is pulled to the right by 4 cm: the restoring force is 8 N to the left. If the spring is returned to equilibrium and then pushed to the left 2 cm, the restoring force is: a. 4 N to the left b. 4 N to the right c. 8 N to the left d. 8 N to the right e. 16 N to the left f. 16 N to the right
B
The end of a spring is pulled to the right by 4 cm; the restoring force is 8 N to the left. If the spring is returned to equilibrium and then pushed to the left 2 cm, the restoring force is: a. 4 N to the left b. 4 N to the right c. 8 N to the left d. 8 N to the right e. 16 N to the left f. 16 N to the right
B
The left figure shows two boys of equal mass standing halfway to the edge on a turntable that is freely rotating at angular speed wi. They then walk to the positions shown in the right figure. The final angular speed wf is a. Greater than wi b. Less than wi c. Equal to wi
B
The spring force is a. In the same direction as the change in the spring's length b. In the opposite direction as the change in the spring's length c. Perpendicular to the change in the spring's length d. Constant regardless of the change in the spring's length
B
The two objects collide and stick together. After the collision the combined objects a. Move to the right as shown b. Move to the left c. Are at rest
B
The work done by kinetic friction is equal to a. fk*Δx b. ΔEth and fk*Δx c. Friction can't do work d. ΔEth
B
Two objects moving at the same speed a. Will have the same kinetic energy if they have the same momentum b. Will have the same kinetic energy if they have the same mass c. Will have different kinetic energies if they are moving in different directions d. Will always have the same kinetic energy
B
100 J is added to a sample of ideal gas as heat. The gas then expands against a piston, doing 70 J of work. During this process a. The temperature of the gas increases b. The temperature of the gas decreases c. The temperature of the gas stays the same
A
A merry-go-round spins freely when Diego moves quickly to the center along a radius of the merry-go-round. As he does this, it is true to say that a. The moment of inertia of the system decreases and the angular speed increases b. The moment of inertia of the system decreases and the angular speed decreases c. The moment of inertia of the system decreases and the angular speed remains the same d. The moment of inertia of the system increases and the angular speed increases e. The moment of inertia of the system increases and the angular speed decreases.
A
A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The clay sticks to the wall. Which one of these objects experiences the greater momentum change? a. The ball b. The clay c. Both them experience the same non-zero momentum change d. Both of them experience zero momentum change
A
A rubber ball bounces off of a wall with an initial speed v and reverses its direction so its speed is v right after the bounce. As a result of this bounce, which of the following quantities of the ball are conserved? (There could be more than one correct choice.) a. The kinetic energy of the ball b. The momentum of the ball c. Both the momentum and the kinetic energy of the ball d. None of the above quantities are conserved
A
As a spring is stretch a greater distance the force of the spring on your hand a. Increases b. Decreases c. Stays the same d. There is not enough information to tell
A
Bars A and B are attached to a wall on the left and pulled with equal forces to the right. Bar B, with twice the radius, is stretched as far as bar A. Which has the larger value of Young's modulus Y? a. YA > YB b. YA = YB c. YA < YB d. Not enough information to tell
A
Forms of potential energy include a. Gravitational and elastic b. Kinetic and thermal c. Thermal and elastic d. Kinetic and gravitational
A
Heat spontaneously moves from a. High temperatures to low temperature b. Heat does not move. c. Low temperature to high temperature d. From high to low and from low to high temperatures
A
How does the work you do to a book when you lift it compare to the energy you used to lift it? a. Energy used is greater than work done b. It is the same amount c. None of these are correct d. Work done is greater than the energy used
A
How many calories are in 1 Calorie? a. 1000 b. They are the same c. 0.001 d. Depends on the process
A
Impulse can be defined as a. Change of momentum b. Change of velocity c. Change of mass d. Change of angular position
A
In an energy diagram, what does the difference between the energy line and the potential energy line represent? a. Kinetic energy b. Change of thermal energy c. Energy leaving the system d. All of these are correct.
A
In order for a force to do no work on an object a. The object is stationary, or the force is perpendicular to the motion b. The force is perpendicular to the direction of motion c. The object is stationary d. All forces must do work
A
In perfectly elastic collisions a. Kinetic energy is always conserved b. All of these are correct c. Kinetic energy is conserved if all objects have the same mass d. Total energy is conserved but kinetic energy is not
A
Inelastic collisions occur when a. The objects stick together b. The masses are all the same c. Bonds between the objects are broken d. There is no compression during the collision
A
Joe and Bill throw identical balls vertically upward. Joe throws his ball with an initial speed twice as high as Bill. If there is no air resistance, the maximum height of Joe's ball will be a. Four times that of Bill's ball b. Two times that of Bill's ball c. Equal to that of Bill's ball d. Eight times that of Bill's ball e. Roughly 1.4 times that of Bill's ball
A
Power refers to a. The rate at which work is done b. The amount of work done relative to the energy used to do it c. The strength of the force doing the work d. The amount of energy transferred
A
Robert pushes the box to the left at constant speed. In doing so, Robert does _____ work on the box. a. Positive b. Negative c. Zero
A
The direction of the momentum vector is a. The same as the velocity b. Random c. Opposite the direction of the velocity d. Perpendicular to the velocity
A
The efficiency of a typical human body (according to the book) is a. 25% b. 20% c. 15% d. 10%
A
The entropy of a system is low if a. Energy is concentrated in one area b. Energy is shared by many objects c. All of these are correct d. Energy is evenly distributed
A
The first law of thermodynamics says a. Energy is conserved b. Energy spontaneously spreads out c. Energy is created from heat flow d. None of these are correct
A
The following pairs of temperatures represent the temperatures of hot and cold reservoirs for heat engines. Which heat engine has the highest possible efficiency? a. 300 C, 30 C b. 250 C, 30 C c. 200 C, 20 C d. 100 C, 10 C e. 90 C, 0 C
A
The lowest point in the potential energy curve on an energy diagram is a. Point of largest velocity b. Point of smallest total energy c. Point of largest total energy d. The turning point
A
The restoring force of three springs is measured as they are stretched. Which spring has the largest spring constant? a. A b. B c. C d. I don't care
A
The restoring force of three springs is measured as they are stretched. Which spring has the largest spring constant? a. A b. B c. C d. They are all equal
A
When a force is applied to an object the work done is a. All of these are possible b. Positive c. Negative d. There is no work
A
When energy is said to be lost due to inefficiencies in the energy transformation, what has happened to the energy? a. It has transformed to a form that isn't useful b. It has done work c. It has disappeared completely d. It is being used as work in another system
A
Which interaction is irreversible? a. Car collision and heat transfer b. Car collision and molecular collision c. Spontaneous transfer of heat d. Molecular collisions e. Car colliding with a wall
A
Which object produces a restoring force? a. All of these b. Leg bone c. Rubber band d. Steel beam e. Spring
A
Bars A and B are attached to a wall on the left and pulled with equal forces to the right. Bar B, with twice the radius, is stretched half a far as bar A. Which has the larger value of Young's modulus Y? a. YA > YB b. YA = YB c. YA < YB d. Not enough information to tell
A (F/A = Y(deltaL/L) Area of B increases by 4. If YB = YA, stretch would be only deltaL/4. Stretch of deltaL/2 means B is "softer" than A)
A 5-kg ball collides inelastically head-on with a 10-kg ball, which is initially stationary. Which of the following statements is true? (There could be more than one correct choice.) a. The magnitude of the change of velocity the 5-kg ball experiences is greater than that of the 10-kg ball b. The magnitude of the change of velocity the 5-kg ball experiences is less than that of the 10-kg ball c. The magnitude of the change of velocity the 5-kg ball experiences is equal to that of the 10-kg ball d. The magnitude of the change of the momentum of the 5-kg ball is equal to the magnitude of the change of momentum of the 10-kg ball e. Both balls lose all their momentum since the collision is inelastic
A & D
A constant force F pushes a particle through a displacement delta r. In which of these three cases does the force do negative work? a. A b. B c. C d. Both A and B e. Both A and C
D
A force pushes the cart for 1 s, starting from rest. To achieve the same speed with a force half as big, the force would need to push for a. 1/4 s b. 1/2 s c. 1 s d. 2 s e. 4 s
D
A local minimum in the potential energy curve of an energy diagram a. None of the above b. Is a turning point c. Is a point of unstable equilibrium d. Is a point of stable equilibrium
D
A spring-loaded gun shoots a plastic ball with a launch speed of 2.0 m/s. If the spring is compressed twice as far, the ball's launch speed will be a. 1.0 m/s b. 2.0 m/s c. 2.8 m/s d. 4.0 m/s e. 16.0 m /s
D
An old fashioned tire swing exerts a force on the branch and a torque about the point where the branch meets the trunk. If you hang the swing closer to the trunk, this will ____ the force and ______ the torque a. Increase, increase b. Not change, increase c. Not change, not change d. Not change, decrease e. Decrease, not change f. Decrease, decrease
D
At the water park Katie slides down each of the frictionless slides shown. At the top she is given a push so that she has the same speed each time. At the bottom of which slide is she moving the fastest? a. Slide A b. Slide B c. Slide C d. Her speed is the same at the bottom of all 3 slides
D
Conservation of angular momentum explains a. The high wind speeds near the eye of a hurricane b. The quick movements of a flying bat c. Lizards twisting in mid-air d. All of the above
D
Determining the velocity of an object influenced by a changing acceleration a. Is impossible b. Can be done using kinematics or conservation with equal difficulty c. Is easier using kinematics d. Is easier using energy conservation
D
Efficiency can be defined as a. What you get out divided by what you paid b. Energy output divided by energy input c. Work done divided by energy used to do the work d. All of these are correct
D
For an object in static equilibrium a. The net torque about every point is different b. None of these are true c. The net torque about every point is a nonzero constant d. The net torque about any point is zero
D
Heat spontaneously moves from a. Low temperature to high temperature b. Heat does not move c. From high to low and from low to high temperatures d. High temperature to low temperature
D
Hooke's law relates a. Change of the length of the spring to the metal the spring is made of b. The spring force to the force used to compress the spring c. Change of the length of the spring to gravity d. The spring force to the change in the length of the spring
D
How does the energy of atoms in a hot object compare to the energy of atoms in a cold object? a. Hot object atoms have more chemical and kinetic energy b. Hot object atoms have more kinetic energy c. Hot object atoms have more potential energy d. Hot object atoms have more potential and kinetic energy e. Hot object atoms have more chemical energy
D
If the units of your answer are kg ∙ m2/s3, which of the following types of quantities could your answer be? (There could be more than one correct choice.) a. Kinetic energy b. Potential energy c. Force d. Power e. Work
D
In order for the angular momentum of a rotating object to be conserved a. Net torque must be constant, but not equal to zero b. Net force must be zero c. Net force must be constant, but not equal to zero d. Net torque must be zero
D
Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct? a. Both do positive work, but person X does four times the work of person Y b. Both do positive work, but person X does twice the work of person Y c. Both do the same amount of positive work d. Both do zero work e. Both do positive work, but person X does one-half the work of person Y.
D
Power can be defined by a. Energy transformed times the time to make the transformation b. Work done divided by the energy used to do it c. Force applied divided by the duration (Δt) of the force d. Energy transformed divided by the time to transform the energy
D
Rank in order, from largest to smallest, the gravitational potential energies of the balls a. 1 > 2 = 4 > 3 b. 1 > 2 > 3 > 4 c. 3 > 2 > 4 > 1 d. 3 > 2 = 4 > 1
D
The change of momentum of a system a. Is zero if the external net force is zero b. Is zero for an isolated system c. Is equal to the net force on the system multiplied be the time interval of the interaction d. All of these are correct
D
The efficiency of this heat engine is a. 1.00 b. 0.60 c. 0.50 d. 0.40 e. 0.20
D
The impulse approximation is used to a. Combine all forces into one force that is perpendicular to the change of momentum b. Add all small forces during a collision c. All of these are correct d. Ignore small forces during a collision
D
The impulse of an interaction can be defined as a. Fmax * Δt b. Fmax * Δx c. Favg * Δx d. Favg * Δt
D
The momentum of an object is a. Mass * a b. Mass * Favg c. Mass * Δx d. Mass * velocity
D
The potential energy curve for a molecule a. Shows the energy needed to break the chemical bond b. Shows the turning points for an oscillation at a given molecular energy c. Can be used to determine the energy available after a chemical bond is broken d. All of these are correct
D
The temperature in your classroom is closest to a. 68K b. 68C c. 50C d. 295K
D
The work done by kinetic friction is equal to a. fk*Δx b. ΔEth c. None of these d. ΔEth and fk*Δx
D
Three balls are thrown from a cliff with the same speed but at different angles. Which ball has the greatest speed just before it hits the ground? a. Ball A b. Ball B c. Ball C d. All balls have the same speed
D
Walking at constant speed requires energy because a. Your body needs to maintain its temperature b. All of these are correct c. Anything moving at a constant speed needs a force to push it d. The feet are continuously accelerating
D
What symbol is used for heat? a. T b. H c. Etherm d. Q
D
When a car is weighed, it is driven slowly on a horizontal floor over a scale that records a reading as the front wheels go over the scale, and then records a second reading as the rear wheels go over the scale. The weight of the car is equal to a. The weight under the front wheels b. The weight under the rear wheels c. The average of the two weights d. The sum of the two weights e. The difference of the two weights
D
When a spring is stretched by 5 cm, its elastic potential energy is 1 J. What will its elastic potential energy be if it is compressed by 10 cm? a. -4 J b. -2 J c. 2 J d. 4 J
D
When solving conservation of energy problems a. Work is zero if the system is isolated b. The change of thermal energy is zero if there is no friction or drag c. Work on the system is added to the initial energy side d. All of these are correct
D
When you walk at a constant speed on level ground, what energy transformation is taking place? a. Echem -> Ug b. Ug -> Eth c. Echem -> K d. Echem -> Eth e. K -> Eth
D
Which form of water has the lowest entropy? a. Steam b. All forms have the same entropy c. Liquid water d. Ice
D
Which object is in static equilibrium? a. Box A b. Box B c. Box C d. Box D
D
Which of the following changes would increase the maximum theoretical efficiency of a heat engine? a. Increase Th b. Increase Tc c. Decrease T d. Decrease Tc e. Increase Th and/or increase Tc d. Increase Th and/or decrease Tc
D
100 J is added to a sample of ideal gas as heat. The gas then expands against a piston, doing 70 J of work. During this process a. The temperature of the gas increases b. The temperature of the gas decreases c. The temperature of the gas stays the same
a
Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when they hit the ground a. Both will have the same kinetic energy b. The heavier one will have twice the kinetic energy of the lighter one c. The heavier one will have four times the kinetic energy of the lighter one d. The heavier one will have half the kinetic energy of the lighter one e. The heavier one will have one-fourth the kinetic energy of the lighter one
B
Two slides have the same height at the top, but one has a short steep slope while the other has a long gentle slope. If they can be considered frictionless, which will produce the largest speed at the bottom? a. Depends on the mass of the person on the slide b. They produce the same speed at the bottom c. The steep slide d. The gradual slide
B
Two-dimensional momentum conservation works a. For a few special cases b. For all collisions c. If the momenta are perpendicular to each other d. if the angle between the original momenta is small
B
Using the average force of an interaction is useful because a. The force can't be measured b. The time dependence of the force can be complicated c. The force has the same magnitude the entire time of the interaction d. The force doesn't last long
B
What happens to entropy when a heat engine does work? a. Entropy increases in the hot reservoir and decreases in the cold reservoir b. Entropy decreases in the hot reservoir and increases in the cold reservoir c. Entropy increases in both reservoirs d. Entropy decreases in both reservoirs
B
What happens to entropy when energy is transformed to thermal energy? a. May or may not decrease b. Increases c. Stays the same d. Decreases
B
Which of the following processes does not involve a change in entropy? a. An electric heater raises the temperature of a cup of water by 20 C b. A ball rolls up a ramp, decreasing in speed as it rolls higher c. A basketball is dropped from 2 m and bounces until it comes to rest d. The sun shines on a black surface and warms it
B
You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You have two choices about what to do with the ball: either catch the ball or deflect it back toward your friend with the same speed as it was originally thrown. Which choice should you make in order to maximize your speed on the skateboard? a. Catch the ball b. Deflect the ball back c. Your final speed on the skateboard will be the same regardless whether you catch the ball or deflect the ball
B
A hammer hits a nail. The force of the nail on the hammer is a. Greater than the force of the hammer on the nail b. Less than the force of the hammer on the nail c. Equal to the force of the hammer on the nail d. Zero
C
A large 75-kg lighting fixture can be hung from wires of identical size and shape made of aluminum, brass, or copper. The values of Young's modulus for these metals are 0.70 × 1011 Pa (aluminum), 0.91 × 1011 (brass), and 1.1 × 1011 (copper). Which wire would stretch the least distance? a. Aluminum b. Brass c. Copper d. They will all stretch the same distance
C
A mosquito and a truck have a head-on collision. Splat! Which has a larger change of momentum? a. The mosquito b. The truck c. They have the same change of momentum d. Can't say without knowing their initial velocities
C
A roller coaster slows as it goes up a hill. The energy transformation is a. Ug -> K b. Ug -> Eth c. K -> Ug d. K -> Eth
C
A small ball with mass M is at rest. It is then struck by a ball with twice the mass, moving at speed v0. The situation after the collision is shown. Is it possible? a. Yes b. No - momentum is not conserved c. No - energy is not conserved d. No - neither momentum or energy is conserved
C
A tiger is running in a straight line. If we double both the mass and speed of the tiger, the magnitude of its momentum will increase by what factor? a. 1 b. 2 c. 4 d. 8 e. 16
C
An object can remain balanced if a. Its center of gravity is to the left of the pivot point b. Its center of gravity is to the right of the pivot points c. Its center of gravity is over the pivot point d. Its mass is equally distributed
C
Angular momentum is defined as a. Mass * velocity b. Mass * angular velocity c. Moment of inertia * angular velocity d. Moment of inertia * velocity
C
Christina throws a javelin into the air. As she propels it forward from rest, she does 270 J of work on it. At its highest point, its gravitational potential energy has increased by 70 J. What is the javelin's kinetic energy at this point? a. 270 J b. 340 J c. 200 J d. -200 J 3. -340 J
C
Energy conservation tells us that the energy of a system can change via a. Work done on or by the system b. Heat transfer c. Work done and/or heat transfer d. The energy of a system cannot change
C
For a particular spring, the spring constant a. Increases as the spring is compressed b. Increases as the spring is stretched c. Is the same regardless of stretching or compressing d. Decreases as the spring is compressed
C
Given the distance x that a spring is compressed, what is the potential energy of the spring? a. 1/2 kx b. 2 kx2 c. 1/2 kx2 d. 2 kx
C
How does gravitational energy depend on the height, h, of an object? a. mh b. mgh2 c. mgh d. mh2
C
In a collision, one way to decrease the force of impact is to a. Increase the momentum b. Decrease the time of the impact c. Increase the time of the impact d. None of these will affect the force
C
In a two-object inelastic collision, how are the final velocities of the objects related? a. There is no relation b. The larger mass has the smaller velocity c. They each have the same velocity d. The larger mass has the larger velocity
C
In order for a force to do no work on an object a. The object must be stationary b. Every force must do work c. Either the object is stationary, or the force is perpendicular to the motion d. The force must be perpendicular to the direction of motion
C
In two-dimensional collisions momentum conservation is a. In the x or y direction, but not both b. In the y direction only c. In both the x and y directions d. In the x direction only
C
Kinetic energy a. Is not in this chapter b. Depends only on the mass of the object c. Depends on the speed and the mass of the object d. Depends on only the speed of the object
C
Kinetic energy of a rolling object a. Is less than that of a non-rotating object with the same speed b. Is zero c. Is greater than that of a non-rotating object with the same speed d. Is the same as a non-rotating object with the same speed
C
The forces on 2 objects during a collision a. Don't exist b. Are in the same direction c. Are in opposite directions d. Are perpendicular to each other
C
The maximum specific power for muscle is about a. 300 W/kg b. 140 W/kg c. 20 W/kg d. 10 W/kg
C
The spring force is larger a. The more the spring is stretched b. None of these c. The more the length of the spring is changed d. The more the spring is compressed
C
The temperature of an ideal gas is a measure of a. The total kinetic energy of the atoms b. The minimum kinetic energy of the atoms c. The average kinetic energy of the atoms d. The maximum kinetic energy of the atoms
C
The total momentum of a system is conserved if a. The velocities don't change b. The masses don't change c. There are no external forces acting on the system d. There are no internal forces acting within the system
C
Two graphs show smoothed force-versus-time data for two collisions. Which force delivers the greater impulse? a. Force A b. Force B c. Both forces deliver the same impulse
C
Two wires are made out of the same metal, but one wire is twice as long as the other wire. Which wire will have the greatest elastic modulus? a. The shorter wire b. The longer wire c. It will be the same for both wires
C
What factors contribute to improving the stability of an object? a. Lower center of gravity alone b. Wider base alone c. Wider base and lower center of gravity d. None of these improve stability
C
What types of potential energy are included in the work energy equation? a. Gravitational potential energy only b. Gravitational and elastic potential energy only c. All forms of potential energy d. Elastic potential energy only
C
When you drop a pebble from height H, it reaches the ground with speed V if there is no air resistance. From what height should you drop it so it will reach the ground with twice speed? a. H b. 2H c. 4H d. 8H e. 16H
C
Which force below does the most work? All three displacements are the same. sin 60 = 0.87, cos60 = 0.50 a. The 10 N force b. The 8 N force c. The 6 N force d. They all do the same work
C
Work is done a. By all forces b. By the component of the force perpendicular to the displacement c. By the component of the force parallel to the displacement d. Only if the entire force is parallel to the displacement
C
Which of the following changes would increase the maximum theoretical efficiency of a heat engine? a. Increase TH b. Increase TC c. Decrease TH d. Decrease TC e. Increase TH and/or increase TC f. Increase TH and/or decrease TC
F
You and your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy of you and your friend, after you both reach the top. a. It is impossible to tell, since the times you both took are unknown b. It is impossible to tell, since the distances you both traveled are unknown c. Your friends gravitational potential energy is greater than yours, because he got to the top faster d. Both of you have the same amount of gravitational potential energy at the top e. Your gravitational potential energy is greater than that of your friend, because you traveled a greater distance in getting to the top
D
You walk 1 km, turn around and run back to where you started. Compare the energy used and the power during the 2 segments. a. The energy used and the power are the same for both b. The energy used is greater while walking, the power is greater while running c. The energy used is greater while running, the power is greater while running d. The energy used is the same for both, the power is greater while running
D
A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill with no air resistance. Which object rises to a greater height? a. The heavy object, because it has greater initial kinetic energy b. The light object, because gravity slows it down less c. The lightweight object, because the force of gravity on it is less d. The heavy object, because it has more mass to carry it up the hill e. They both slide to exactly the same height
E
A machine uses 1000 J of electric energy to raise a heavy mass, increasing its potential energy by 300 J. What is the efficiency of this process? a. 100% b. 85% c. 70% d. 35% e. 30%
E
A tow rope pulls a skier up the slope at constant speed. What energy transfer (or transfers) is taking place? a. W -> Ug b. W -> K c. W -> Eth d. Both A and B e. Both A and C
E
The cart's change of momentum deltapx is a. -20 kg m/s b. -10 kg m/s c. 0 kg m/s d. 10 kg m/s e. 30 kg m/s
E
What are the two primary energy transfer processes? a. Energy cannot be transferred b. Heat and light c. Nuclear and heat d. Work and nuclear e. Work and heat
E
Which one of the following is a true statement? a. The second law of thermodynamics is a consequence of the first law of thermodynamics b. It is possible for heat to flow spontaneously from a hot body to a cold one or from a cold one to a hot one, depending on whether or not the process is reversible or irreversible c. It is not possible to convert work entirely into heat d. It is impossible to transfer heat from a cooler to a hotter body e. All of these statements are false
E
