AP Physics MCQ Quiz

Two satellites are in circular orbits around Earth. Satellite A has speed vA. Satellite B has an orbital radius nine times that of satellite A. What is the speed of satellite B?

B vA/3

Block Y with mass mYmY falls onto and sticks to block X, which is attached to a vertical spring, as shown in Figure 1. A short time later, as shown in Figure 2, the blocks are momentarily at rest. At that moment, block Y exerts a force of magnitude FdownFdown on block X, and block X exerts a force of magnitude Fup on block Y. Which of the following correctly relates Fup, Fdown, and mYg at the instant shown in Figure 2 ?

A (Fup=Fdown)>mYg

A ball of mass M and speed v collides head-on with a ball of mass 2M and speed v/2, as shown above. If the two balls stick together, their speed after the collision is

A 0

The cart of mass 10 kg shown above moves without frictional loss on a level table. A 10 N force pulls on the cart horizontally to the right. At the same time, a 30 N force at an angle of 60° above the horizontal pulls on the cart to the left. What is the magnitude of the horizontal acceleration of the cart?

A 0.5 m/s^2

On Earth, when a box slides across a horizontal board, the board exerts a frictional force of magnitude F0F0 on the box. The board and the box are moved to a planet with twice the radius but one-third the mass of Earth. When the box slides across the board, the frictional force exerted by the board on the box is now

A 1/12 Fo

A ball of mass m and momentum p has kinetic energy equal to which of the following?

A 1/2 p^2/m

Two objects of mass 0.2 kg and 0.1 kg, respectively, move parallel to the x-axis, as shown above. The 0.2 kg object overtakes and collides with the 0.1 kg object. Immediately after the collision, the y-component of the velocity of the 0.2 kg object is 1 m/s upward. What is the y-component of the velocity of the 0.1 kg object immediately after the collision?

A 2 m/s downward

Block A of mass 2.0 kg is released from rest at the top of a 3.6 m long plane inclined at an angle of 30º, as shown in the figure above. After sliding on the horizontal surface, block A hits and sticks to block B, which is at rest and has mass 3.0 kg. Assume friction is negligible. The speed of the blocks after the collision is most nearly

A 2.4 m/s

The graph above shows the force exerted by a spring as a function of the length of the spring. A block on a frictionless table is pushed against the spring that is fastened to a wall. The spring is compressed until its length is 20 cm. The block is then released. Which of the following values is closest to the kinetic energy with which the block leaves the spring?

A 3J

While traveling in its elliptical orbit around the Sun, Mars gains speed during the part of the orbit where it is getting closer to the Sun. Which of the following can be used to explain this gain in speed?

A As Mars gets closer to the Sun, the Mars-Sun system loses potential energy and Mars gains kinetic energy.

A box is given a sudden push up a ramp. Friction between the box and the ramp is not negligible. Which of the following diagrams best represents the directions of the actual forces acting on the box as it moves upward after the push?

A Box on incline with arrows going down to the left and up

Carts 1 and 2 are initially moving toward each other, as shown in the top figure. The carts collide and afterward are both moving to the right, as shown in the bottom figure. If the positive direction is to the right, which of the following best represents the force exerted on each cart by the other during the collision as a function of time?

A Cart 2 graphed in Q1 (dashed line) Cart 1 graphed in Q4 (normal line) Curve is the same size

An elevator carrying a person of mass m is moving upward and slowing down. How does the magnitude F of the force exerted on the person by the elevator floor compare with the magnitude mg of the gravitational force?

A F < mg

A force of constant magnitude F and fixed direction acts on an object of mass m that is initially at rest. If the force acts for a time interval ∆t over a displacement ∆x , what is the magnitude of the resultant change in the linear momentum of the object?

A F ∆t

An object is moving in the positive x-direction while a net force directed along the x-axis is exerted on the object. The figure above shows the force as a function of position. What is the net work done on the object over the distance shown?

A F0d

The figures above show a small block of mass 0.20kg0.20kg on a track in the shape of a circular arc. The block is released from rest at a height HH above the floor, as shown in Figure 11. The block slides along the track with negligible friction and leaves it at a height of 0.40m0.40m above the floor and a speed of 3.0m/s3.0m/s at a 30°30° angle, as shown in Figure 22. The magnitude of the gravitational force exerted on the block is FgFg, and the magnitude of the normal force exerted by the track on the block is FnFn. Which of the following correctly compares the magnitudes of these two forces when the block is at the lowest point on the track?

A Fn>Fg

Two satellites are in circular orbits around Earth. Satellite 11 has mass m0m0 and an orbital radius of 2RE, where RE is the radius of Earth. Satellite 2 has mass 2m0 and an orbital radius of 3RE. Which of the following correctly compares the magnitude FF of the force exerted by Earth on each satellite and the speed vv of each satellite?

A Force: F1>F2 Speed: v1>v2

Three forces act on an object. If the object is in translational equilibrium, which of the following must be true? I. The vector sum of the three forces must equal zero II. The magnitudes of the three forces must be equal III. All three forces must be parallel.

A I only

Block A is set on a rough horizontal table and is connected to a horizontal spring that is fixed to a wall, as shown. Block A is then also connected to hanging block B by a lightweight string that passes over an ideal pulley, as shown. The friction force exerted on block A by the table is not negligible. The blocks are initially held at rest so that the spring is not stretched. When the blocks are released, hanging block B moves downward and block A on the table moves to the right until the system comes again to rest. Let E1 be the mechanical energy of the blocks-spring system, and let E2 be the mechanical energy of the blocks-spring-Earth system. How do these two energies change from when the blocks are held at rest to when the blocks come to rest again?

A Increases Decreases

Block 1 of mass m1 and block 2 of mass m2 are sliding along the same line on a horizontal frictionless surface when they collide at time tc. The graph above shows the velocities of the blocks as a function of time. How does the kinetic energy of the two-block system after the collision compare with its kinetic energy before the collision, and why?

A It is less, because the blocks have the same velocity after the collision, so some of their kinetic energy was transformed into internal energy.

A cart of mass m is moving with negligible friction along a track with known speed v1 to the right. It collides with and sticks to a cart of mass 4m moving with known speed v2 to the right. Which of the two principles, conservation of momentum and conservation of mechanical energy, must be applied to determine the final speed of the carts, and why?

A Only conservation of momentum, because the momentum lost by one cart is gained by the other and there is only one unknown quantity.

A railroad car of mass m is moving with speed u when it collides with and connects to a second railroad car of mass 3m, initially at rest, as shown above. How do the speed and kinetic energy of the connected cars compare to those of the single car of mass m before the collision?

A Speed: Less Kenetic Energy: Less

Two blocks, of mass m and 2m, are initially at rest on a horizontal frictionless surface. A force F is exerted individually on each block, as shown above. The graph shows how F varies with time t. Which block has the greatest average power provided to it between t = 0 s and t = 3 s?

A The block of mass m

A sled slides down a hill with friction between the sled and hill but negligible air resistance. Which of the following must be correct about the resulting change in energy of the sled-Earth system?

A The sum of the kinetic energy and the gravitational potential energy changes by an amount equal to the energy dissipated by friction.

A block with mass m is at rest on a rough incline, as shown in the figure above. Which of the following forces must have a magnitude equal to mg? Select two answers

A The total force exerted on the block by the incline D The gravitational force exerted on Earth by the block

In trial 1 of an experiment, a cart moves with speed v0 on a frictionless, horizontal track and collides elastically with another cart that is initially at rest. In trial 2, the setup is identical except that the carts stick together during the collision. How does the speed of the two-cart system's center of mass change, if at all, during the collision in each trial?

A Trial 1: does not change Trial 2: Does not change

Two skaters are initially at rest next to each other on frictionless ice. Skater A pushes on skater B. If skater A has greater mass than skater B, which of the following correctly relates the magnitudes of their momentums p and their kinetic energies K after the push?

A pA=pB and Ka < Kb

A 1.0 kg block is attached to an unstretched spring of spring constant 50 N/m and released from rest from the position shown in Figure 1 above. The block oscillates for a while and eventually stops moving 0.20 m below its starting point, as shown in Figure 2. What is the change in potential energy of the block-spring-Earth system between Figure 1 and Figure 2 ?

A −1.0 J

The figure above shows a uniform meterstick that is set on a fulcrum at its center. A force of magnitude F toward the bottom of the page is exerted on the meterstick at the position shown. At which of the labeled positions must an upward force of magnitude 2F be exerted on the meterstick to keep the meterstick in equilibrium?

B B

A block released from rest at position A slides with negligible friction down an inclined track, around a vertical loop, and then along a horizontal portion of the track, as shown above. The block never leaves the track. After the block is released, in which of the following sequences of positions is the speed of the block ordered from fastest to slowest?

B B E C D

Objects X and Y are constrained to move along a straight line. The graphs above show the net force exerted along that line on each of the objects as functions of time. Which of the following correctly ranks the change in momentum Δp of the objects?

B ΔpX=ΔpY

A moon is in an elliptical orbit about a planet as shown above. At point A the moon has speed μA and is at distance RA from the planet. At point B the moon has speed μB. Which of the following explains a correct method for determining the distance of the moon from the planet at point B in terms of the given quantities?

B Conservation of angular momentum, because the gravitational force exerted on the moon is always directed toward the planet

A vertical spring launcher is attached to the top of a block and a ball is placed in the launcher, as shown in the figure. While the block slides at constant speed to the right across a horizontal surface with negligible friction between the block and the surface, the ball is launched upward. When the ball reaches its maximum height, what will be the position of the ball relative to the spring launcher?

B Directly above the spring launcher

A horizontal, uniform board of weight 125 N and length 4 m is supported by vertical chains at each end. A person weighing 500 N is sitting on the board. The tension in the right chain is 250 N. How far from the left end of the board is the person sitting?

B 1.5 m

What is the kinetic energy of a satellite of mass m in that orbits the Earth, of mass M, in a circular orbit of radius R ?

B 1/2 GMm/R

A block of mass 3 kg slides along a horizontal surface that has negligible friction except for one section, as shown above. The block arrives at the rough section with a speed of 5 m/s and leaves it 0.5 s later with a speed of 3 m/s. What is the magnitude of the average frictional force exerted on the block by the rough section of the surface?

B 12 N

Two objects, A and B, initially at rest, are "exploded" apart by the release of a coiled spring that was compressed between them.As they move apart, the velocity of object A is 5 m/s and the velocity of object B is -2 m/s. The ratio of the mass of object A to the mass of object B, mA/mB, is

B 2/5

A new planet is discovered that has twice the Earth's mass and twice the Earth's radius. On the surface of this new planet, a person who weighs 500 N on Earth would experience a gravitational force of

B 250 N

A horizontal, uniform board of weight 125 N and length 4 m is supported by vertical chains at each end. A person weighing 500 N is sitting on the board. The tension in the right chain is 250 N. What is the tension in the left chain?

B 375 N

A 12 kg box sliding on a horizontal floor has an initial speed of 4.0 m/s. The coefficient of friction between the box and the floor is 0.20. The box moves a distance of 4.0 m in 2.0 s. The magnitude of the change in momentum of the box during this time is most nearly

B 48 kg⋅m/s

A child has a toy tied to the end of a string and whirls the toy at constant speed in a horizontal circular path of radius R. The toy completes each revolution of its motion in a time period T. What is the magnitude of the acceleration of the toy?

B 4π^2R / T^2

A rope of negligible mass supports a block that weighs 30 N, as shown above. The breaking strength of the rope is 50 N. The largest acceleration that can be given to the block by pulling up on it with the rope without breaking the rope is most nearly

B 6.7 m/s2

A block of known mass hanging from an ideal spring of known spring constant is oscillating vertically. A motion detector records the position, velocity, and acceleration of the block as a function of time. Which of the following indicates the measured quantities that are sufficient to determine whether the net force exerted on the block equals the vector sum of the individual forces?

B Acceleration and position only

A cart is moving on a level track in the positive x-direction. A force acting parallel to the x-axis is exerted on the cart. The graph above shows the net force exerted on the cart as a function of displacement. As the cart travels from x = 0 m to x = 4 m , what is the net change in the kinetic energy of the cart?

B An increase of 10 J

An object of mass m is initially at rest and free to move without friction in any direction in the xy-plane. A constant net force of magnitude F directed in the +x direction acts on the object for 1 s. Immediately thereafter a constant net force of the same magnitude F directed in the +y direction acts on the object for 1 s. After this, no forces act on the object. Which of the following vectors could represent the velocity of the object at the end of 3 s, assuming the scales on the x and y axes are equal?

B Graph with a small arrow and slight linear line (close to x asis but not on)

An object of mass m is initially at rest and free to move without friction in any direction in the xy-plane. A constant net force of magnitude F directed in the +x direction acts on the object for 1 s. Immediately thereafter a constant net force of the same magnitude F directed in the +y direction acts on the object for 1 s. After this, no forces act on the object. Which of the following graphs best represents the kinetic energy K of the object as a function of time?

B Graph: from 0 to 1 slight curve from 1 to 2: slight curve from 2 to 3 straight line

In a classroom at time t = 0 , a sphere is thrown upward at a 45° angle to the horizontal. At time t1, while the sphere is still rising, it bounces off the ceiling elastically and with no friction. Which of the following pairs of graphs could represent the sphere's horizontal velocity and vertical velocity as functions of time t?

B Horizontal velocity graph: straight line in Q1 Vertical veloity graph: Slight slope going down towards t1, at point t1 straigh line down, after t1 line continues to be linear slightly sloped down

Three objects can only move along a straight, level path. The graphs below show the position d of each of the objects plotted as a function of time t. Graph 1: linear Graph 2: Constant Graph 3: quadratic The magnitude of the momentum of the object is increasing in which of the cases?

B III only

Two identical blocks A and B are connected by a lightweight rope. Block A is pulled to the right by a constant force F0. The blocks are moving to the right across a rough surface and approach point P, where the rough surface transitions to a surface with negligible friction. How does the tension, T, in the rope connecting the blocks change, if at all, as block A passes point P?

B T increases.

The angular momentum of a rigid body rotating around a fixed point as a function of time is shown in the graph. Which of the following statements are true? Select two answers.

B The angular acceleration of the object is constant. D The net torque applied to the object is constant

Block 1 of mass m1 and block 2 of mass m2 are sliding along the same line on a horizontal frictionless surface when they collide at time tc. The graph above shows the velocities of the blocks as a function of time. Which of the following is true of the motion of the center of mass of the two-block system during the time shown?

B The center of mass moves at a constant velocity of +1.0 m/s because there is no friction acting on the system.

The diagram above shows a top view of a child of mass M on a circular platform of mass 2M that is rotating counterclockwise. Assume the platform rotates without friction. Which of the following describes an action by the child that will increase the angular speed of the platform-child system and gives the correct reason why?

B The child moves toward the center of the platform, decreasing the rotational inertia of the system.

A soft foam block of mass m slides without friction in the positive x-direction with speed v. At time t = 0 , a student briefly pushes the block with a force probe in the positive x-direction. The graph above shows the force probe's measurements as a function of time during the push. Which of the following statements is true about the block's momentum between t = 0 and t = t1?

B The momentum of the block has increased by approximately 1/2 F0t1

A cart is constrained to move along a straight line. A varying net force along the direction of motion is exerted on the cart. The cart's velocity v as a function of time t is shown in the graph above. The five labeled points divide the graph into four sections. During some part of the motion, the work done on the cart is negative. What feature of the motion indicates this?

B The speed is decreasing.

The diagram shows the forces exerted on a block that starts from rest and speeds up as it moves down a rough incline near Earth's surface. Which of the following statements are true? Select two answers.

B The total mechanical energy of the block-Earth system decreases as the block slides down the incline. C The momentum of the block increases as the block slides down the incline

A bicycle wheel of known rotational inertia is free to rotate about its central axis. With the wheel initially at rest, a student wraps a string around the wheel and pulls the string with a spring scale, causing the wheel to rotate. The student records the tension in the string and the time for which the string was pulled. Without measuring the wheel's final angular speed, can the student find the magnitude of the wheel's final angular momentum, and what is a correct explanation?

B Yes. The student also needs to measure the wheel's radius to calculate the torque exerted on the wheel.

A student uses a spring scale to exert a horizontal force on a block, pulling the block over a smooth floor. The student repeats the procedure several times, each time pulling the block from rest through a distance of 1.0 m. For which of the following graphs of force as a function of distance will the block be moving the fastest at the end of the 1.0 m?

B graph with straight line then up then straight libe

In the setup shown above, a student uses motion detector 11 to measure the speed vivi of a cart with mass mm before it collides with and sticks to a stationary cart with mass MM. Motion detector 22 measures the speed vfvf of the carts after the collision. The student repeats the experiment several times using different values of vivi and creates a graph of vfvf as a function of vivi. The slope of this graph is most nearly equal to

B m/M + m

Blocks A and B, of masses mA and mB, are at rest on a frictionless surface, as shown above, with block A fixed to the table. Block C of mass mC is suspended by a string that is tied to block B over an ideal pulley. Which of the following gives the magnitude of the force exerted by block A on block B ?

B mCg

A solid metal ball and a hollow plastic ball of the same external radius are released from rest in a large vacuum chamber. When each has fallen 1 m, they both have the same

B speed

A solid disk whose plane is parallel to the ground spins with an initial angular speed ω0. Three identical blocks are dropped onto the disk at locations A, B, and C, one at a time, not necessarily in that order. Each block instantaneously sticks to the surface of the disk, slowing the disk's rotation. A graph of the angular speed of the disk as a function of time is shown. The blocks are now dropped in the reverse order and the final angular speed of the disk is ω2. How does ω2 compare to ω1, the final angular speed shown on the graph from the initial experiment?

B ω2=ω1

A force F0 is applied continuously to a box initially at rest on a horizontal surface. The box slides with negligible friction for equal distances d1d1 and d2, as shown. How does the kinetic energy gained by the block over distance interval d2, 2∆K2, compare to the kinetic energy gained over distance interval d1d1, ∆K1, and why?

B ∆K2=∆K1, because the applied force does the same work on the block over intervals d1 and d2.

A rocket lifts a payload upward from the surface of Earth. The radius of Earth is R, and the weight of the payload on the surface of Earth is W. The force of Earth's gravity on the payload is W/2 when the rockets ditance from the senter of Earth is

B √2R

A projectile fired into the air explodes and splits into two halves of equal mass that hit the ground at the same time. If the projectile had not exploded, it would have landed at point X, which is a distance R to the right of the launch point. After the explosion, one of the halves lands at point Y, which is a distance 2R to the right of the launch point. If air resistance is negligible, where did the other half land?

B At the launch point

An object has a weight W when it is on the surface of a planet of radius R. What will be the gravitational force on the object after it has been moved to a distance of 4R from the center of the planet?

E 1/16 W

The figures above show a small block of mass 0.20kg on a track in the shape of a circular arc. The block is released from rest at a height H above the floor, as shown in Figure 1. The block slides along the track with negligible friction and leaves it at a height of 0.40m above the floor and a speed of 3.0m/sat a 30° angle, as shown in Figure 2.

C 0.86m

A rubber ball with mass 0.20 kg is dropped vertically from a height of 1.5 m above a floor. The ball bounces off of the floor, and during the bounce 0.60 J of energy is dissipated. What is the maximum height of the ball after the bounce?

C 1.2 m

A block of mass 2.0 kg2.0 kg, starting from rest, is pushed with a constant force across a horizontal track. The position of the block as a function of time is recorded, and the data are shown in the table. What is the magnitude of the change in momentum of the block between zero and 4.04.0 seconds?

C 1.6 kg⋅m/s

A 2 kg block, starting from rest, slides 20 m down a frictionless inclined plane from X to Y, dropping a vertical distance of 10 m as shown above. The speed of the block at point Y is most nearly

C 14 m/s

A ball of mass 0.4 kg is initially at rest on the ground. It is kicked and leaves the kicker's foot with a speed of 5.0 m/s in a direction 60° above the horizontal. The magnitude of the impulse imparted by the ball to the foot is most nearly

C 2 N▪s

The wheel on a vehicle has a rotational inertia of 2.0 kg⋅m2. At the instant the wheel has a counterclockwise angular velocity of 6.0 rad/s, an average counterclockwise torque of 5.0 N⋅m is applied, and continues for 4.0 s. What is the change in angular momentum of the wheel?

C 20 kg⋅m2/s

The system shown above is released from rest. If friction is negligible, the acceleration of the 4.0 kg block sliding on the table shown above is most nearly

C 3.3 m/s^2

In a lab, a block weighing 80 N is attached to a spring scale, and both are pulled to the right on a horizontal surface, as shown above. Friction between the block and the surface is negligible. What is the acceleration of the block when the scale reads 32 N?

C 4.0 m/s^2

A student obtains data on the magnitude of force applied to an object as a function of time and displays the data on the graph above. Answer the following question for the information and diagram above. The increase in the momentum of the object between t = 0 s and t = 4 s is most nearly

C 60 N·s

An object weighing 120 N is set on a rigid beam of negligible mass at a distance of 3 m from a pivot, as shown above. A vertical force is to be applied to the other end of the beam a distance of 4 m from the pivot to keep the beam at rest and horizontal. What is the magnitude F of the force required?

C 90 N

A student on another planet has two identical spheres, each of mass 0.6 kg, attached to the ends of a rod of negligible mass. The student gives the assembly a rotation in the vertical plane and then releases it so it falls, as shown in the top figure above. Sensors record the vertical velocity of the two spheres, and the data is shown in the graph of velocity v as a function of time t. Another student wants to calculate the assembly's angular speed and the change in the linear momentum of the center of mass of the assembly between 0 s and 0.3 s. Which of these quantities can be determined using the graph?

C Angular speed and change in linear momentum

The figure shows three cases where two spheres are touching and attract each other with the gravitational force. The radii of the spheres in each case are shown. All of the spheres are made of material with the same density. Which of the following correctly ranks these cases based on the gravitational force between the spheres?

C B>C>A

A box experiences a varying net force that changes its velocity. The graph shows the velocity of the box as a function of time. Which of the following correctly describes the net work, Wnet, done on the box for the given intervals of time?

C Between 0 and t1 Wnet=0 Between t1 and t2 Wnet=0 Between t2 and t3 Wnet<0

A block released from rest at position A slides with negligible friction down an inclined track, around a vertical loop, and then along a horizontal portion of the track, as shown above. The block never leaves the track. The gravitational potential energy and the kinetic energy of the block are most nearly equal at which position? (Consider the potential energy to be zero at position B.)

C C

Two lab carts have the same mass and are free to move on a horizontal track. The carts' wheels have negligible mass. Cart 1 travels to the right at 1.0 m/s and collides with cart 2, which is initially at rest, as shown at left above. Cart 2 has a compressed spring-loaded plunger with a nonnegligible amount of stored energy. During the collision, the spring-loaded plunger pops out, staying in contact with cart 1 for 0.10 s as the spring decompresses. Negligible mechanical energy dissipates during the collision. Taking rightward as positive, the carts' velocities after the collision could be which of the following? Select two answers.

C Cart 1: -0.5 m/s Cart 2: 1.5 m/s D Cart 1: -1.0 m/s Cart 2: 2.0 m/s

A satellite of mass m and speed v moves in a stable, circular orbit around a planet of mass M. What is the radius of the satellite's orbit?

C GM/v^2

Three objects can only move along a straight, level path. The graphs below show the position d of each of the objects plotted as a function of time t. Graph I: linear Graph 2: constant Graph 3:exponential The sum of the forces on the object is zero in which of the cases?

C I and II only

Which of the following is true of the conservation of momentum and kinetic energy?

C Kinetic energy is conserved only in elastic collisions.

Block A hangs from a light string that passes over a light pulley and is attached to block B, which is on a level horizontal frictionless table, as shown above. Students are to determine the mass of block B from the motion of the two-block system after it is released from rest. They plan to measure the time block A takes to reach the floor. The students must also take which of the following measurements to determine the mass of block B?

C Only the mass of block A and the distance block A falls to reach the floor

An object is initially at rest. A varying force is applied to the object as shown in the graph. Which of the following correctly explains the momentum of the object at time t=7st?.

C The final momentum of the object is negative because the magnitude of the area bounded by the graph and the horizontal axis is less from t=0st=0s to t=2s than from t=2s to t=7s.

Two people of unequal mass are initially standing still on ice with negligible friction. They then simultaneously push each other horizontally. Afterward, which of the following is true?

C The momenta of the two people are of equal magnitude.

The motion of an object is shown in the velocity-time graph. Which best describes the motion of the object?

C The object travels in the same direction for the entire time.

A massless rigid rod of length 3d is pivoted at a fixed point W, and two forces each of magnitude F are applied vertically upward as shown above. A third vertical force of magnitude F may be applied, either upward or downward, at one of the labeled points. With the proper choice of direction at each point, the rod can be in equilibrium if the third force of magnitude F is applied at point

C V or X only

An open cart on a level surface is rolling without frictional loss through a vertical downpour of rain, as shown above. As the cart rolls, an appreciable amount of rainwater accumulates in the cart. The speed of the cart will

C decrease because of conservation of momentum

Two massive, positively charged particles are initially held a fixed distance apart. When they are moved farther apart, the magnitude of their mutual gravitational force changes by a factor of n. Which of the following indicates the factor by which the magnitude of their mutual electrostatic force changes?

C n

An empty sled of mass M moves without friction across a frozen pond at speed v0. Two objects are dropped vertically into the sled one at a time: first an object of mass m and then an object of mass 2m. Afterward the sled moves with speed vf. What would be the final speed of the sled if the objects were dropped into it in reverse order?

C vf

Two identical blocks are connected by a lightweight string that passes over a lightweight pulley that can rotate about its axle with negligible friction. The two-block system is released from rest and the blocks accelerate. Which of the following correctly relates the potential energy gained by the block 1-Earth system |∆U1|to the potential energy lost by the block 2-Earth system |∆U2|and provides correct evidence?

C |∆U1|<|∆U2|, because the two-block system gains kinetic energy.

A blue sphere and a red sphere with the same diameter are released from rest at the top of a ramp. The red sphere takes a longer time to reach the bottom of the ramp. The spheres are then rolled off a horizontal table at the same time with the same speed and fall freely to the floor. Which sphere reaches the floor first?

D Neither; the spheres reach the floor at the same time.

A rock of mass m is thrown horizontally off a building from a height h, as shown above. The speed of the rock as it leaves the thrower's hand at the edge of the building is vo What is the kinetic energy of the rock just before it hits the ground?

D 1/2 mv20 + mgh

An object is moving to the west at a constant speed. Three forces are exerted on the object. One force is 10 N directed due north, and another is 10 N directed due west. What is the magnitude and direction of the third force if the object is to continue moving to the west at a constant speed?

D 10√2 N , directed southeast

A student sets an object attached to a spring into oscillatory motion and uses a position sensor to record the displacement of the object from equilibrium as a function of time. A portion of the recorded data is shown in the figure above. The frequency of oscillation is most nearly

D 2.0 Hz

The figure above shows the forces exerted on a block that is sliding on a horizontal surface: the gravitational force of 40 N, the 40 N normal force exerted by the surface, and a frictional force exerted to the left. The coefficient of friction between the block and the surface is 0.20. The acceleration of the block is most nearly

D 2.0 m/s^2 to the left

A student sets an object attached to a spring into oscillatory motion and uses a position sensor to record the displacement of the object from equilibrium as a function of time. A portion of the recorded data is shown in the figure above. The total distance traveled by the object between 0.35 s and 0.40 s is most nearly

D 2cm

The two blocks of masses M and 2M shown above initially travel at the same speed v but in opposite directions. They collide and stick together. How much mechanical energy is lost to other forms of energy during the collision?

D 4/3 Mv^2

A block of mass 3 kg slides along a horizontal surface that has negligible friction except for one section, as shown above. The block arrives at the rough section with a speed of 5 m/s and leaves it 0.5 s later with a speed of 3 m/s. What is the magnitude of the work done by the frictional force exerted on the block by the rough section of the surface?

D 6 J

A solid disk whose plane is parallel to the ground spins with an initial angular speed ω0. Three identical blocks are dropped onto the disk at locations A, B, and C, one at a time, not necessarily in that order. Each block instantaneously sticks to the surface of the disk, slowing the disk's rotation. A graph of the angular speed of the disk as a function of time is shown.

D B, A, C

Block 1 of mass m1 and block 2 of mass m2 are sliding along the same line on a horizontal frictionless surface when they collide at time tc. The graph above shows the velocities of the blocks as a function of time. Which block has the greater mass, and what information indicates this?

D Block 2, because the final velocity is closer to the initial velocity of block 2 than it is to the initial velocity of block 1.

Four rods, each of mass MM, are pinned at the left end to the horizontal surface of a table and are shown from above in the following figures. Each rod is free to rotate about a pivot at its left end with negligible friction. In each case, forces are exerted on the rod with different magnitudes and in different directions as shown. The rotational inertia of a rod of mass M and length L about the end of the rod is 1/3 ML^2. In which cases do the rods experience equal initial angular accelerations? Select two answers.

D Dot with pole L off of it and a force of 2F on a 60 degree angle

A small car with mass m and speed 2v and a large car with mass 2m and speed v both travel the same circular section of an unbanked road. If the frictional force required to keep the small car on the road without skidding is F, then the frictional force required to keep the large car on the road without skidding is

D F/2

Two astronauts are connected by a taut cable and are initially at rest with respect to a nearby space station. Astronaut X throws a large container to Astronaut Y. Figure 1 above shows the astronauts immediately after the container is thrown by Astronaut X, and Figure 2 shows the astronauts immediately after the container is caught by Astronaut Y. Which of the following describes the motion of Astronaut Y in Figures 1 and 2 ?

D Figure 1: moves to the left Figure 2: Does not move

A stationary object explodes, breaking into three pieces of masses m, m, and 3m. The two pieces of mass m move off at right angles to each other with the same magnitude of momentum mV, as shown in the diagram above. What are the magnitude and direction of the velocity of the piece having mass 3m ?

D Magnitude: √2V/3 Direction: Left and Down

A person exerts an upward force on a box, as shown above. The box may be moving upward, downward, or not at all while the person exerts the upward force. For which of the following motions of the box is the work done by the person on the box correctly indicated?

D Motion of Box: Downward with increasing speed Work done by Person on Box: Negative

A student is asked to move a box from ground level to the top of a loading dock platform, as shown in the figures above. In Figure 1, the student pushes the box up an incline with negligible friction. In Figure 2, the student lifts the box straight up from ground level to the loading dock platform. In which case does the student do more work on the box, and why?

D Neither method, because the work is the same in both cases, since using the ramp decreases the force by the same factor that it increases the distance

Steel sphere A of mass M is moving along a horizontal surface with constant speed v. Identical steel sphere B is at rest and hangs on a string of length R attached to a support at point P, as shown in the figure above. The spheres collide, and as a result sphere A stops and sphere B swings a vertical height h before coming momentarily to rest. Knowing values for which of the following will allow determination of the angular impulse on sphere B with respect to P due to the collision?

D R, M, and v

Two objects are released from rest at the top of ramps with the same dimensions, as shown in the figure above. The sphere rolls down one ramp without slipping. The small block slides down the other ramp without friction. Which object reaches the bottom of its ramp first, and why?

D The block, because it does not gain rotational kinetic energy, but the sphere does

Two objects, A and B, move toward one another. Object A has twice the mass and half the speed of object B. Which of the following describes the forces the objects exert on each other when they collide and provides the best explanation?

D The forces exerted by each object on the other are the same, because interacting objects cannot exert forces of different magnitude on each other.

A student sets an object attached to a spring into oscillatory motion and uses a position sensor to record the displacement of the object from equilibrium as a function of time. A portion of the recorded data is shown in the figure above.

D The slope of the tangent to a best-fit sinusoidal curve at 0.65 s

Three spheres, with masses indicated above, are initially far away from each other, and the gravitational potential energy of the three-sphere system is zero. The spheres are then brought together until each sphere is a distance r from the other two, as shown above. What is the new gravitational potential energy of the three-sphere system?

D −5Gm^2/r

A 2 kg block, starting from rest, slides 20 m down a frictionless inclined plane from X to Y, dropping a vertical distance of 10 m as shown above. The magnitude of the net force on the block while it is sliding is most nearly

E 10.0 N

A constant force of 900 N pushes a 100 kg mass up the inclined plane shown above at a uniform speed of 4 m/s. The power developed by the 900 N force is most nearly

E 3600 W

A block of mass 2 kg slides along a horizontal tabletop. A horizontal applied force of 12 N and a vertical applied force of 15 N act on the block, as shown above. If the coefficient of kinetic friction between the block and the table is 0.2, the frictional force exerted on the block is most nearly

E 7 N

A compressed spring mounted on a disk can project a small ball. When the disk is not rotating, as shown in the top view above, the ball moves radially outward. The disk then rotates in a counterclockwise direction as seen from above, and the ball is projected outward at the instant the disk is in the position shown above. Which of the following best shows the subsequent path of the ball relative to the ground?

E Circle with arrow pointing counter clockwise and liner arrow pointing upwards coming out of sping

A planet of mass m orbits a star of mass M, where m<<M. The orbit is circular, its radius is r, and its period is T. True statements about the planet's orbit include which of the following? I. The orbital speed equals 2πr / T II. The gravitational force equals GMm / r2 III. If the orbital radius r were greater, T would also be greater.

E I, II, and III

A block released from rest at position A slides with negligible friction down an inclined track, around a vertical loop, and then along a horizontal portion of the track, as shown above. The block never leaves the track. Which of the following is true of the net force on the block when it is at position C ?

E It has components both to the left and vertically downwar

How does an air mattress protect a stunt person landing on the ground after a stunt?

E It lengthens the stopping time of the stunt person and reduces the force applied during the landing

For which of the following motions of an object must the acceleration always be zero? I. Any motion in a straight line II. Simple harmonic motion III. Any motion in a circle

E None of these motions guarantees zero acceleration.

A steel ball supported by a stick rotates in a circle of radius r, as shown above. The direction of the net force acting on the ball when it is in the position shown is indicated by which of the following?

E dotted circle with arrow pointed towards center

The figures show a cart moving over the top of a hill (Case 1), moving at the bottom of a dip (Case 2), and moving at the top of a vertical loop (Case 3). In each case, the normal force acting on the car is FnFn and the weight of the car is FgFg. In which case is it always true that Fn>FgFn>Fg, and in which case is it always true that Fn<FgFn<Fg?

Fn>FgAlways Case 2 Fn<FgAlways Case 1

A block is held at rest against a compressed spring at point A at the top of a frictionless track of height hh, as shown above. The block is released, loses contact with the spring at point B, and slides along the track until it passes point C, also at height hh. How do the potential energy U of the block-Earth system and the kinetic energy K of the block at point C compare with those at point A ?

Potential Energy of Block-Earth System: Uc = Ua Kenitic Energy of Block: Kc > Ka

Cylindrical disk A is rotating freely about an axis when an identical disk B that is not rotating is dropped directly on top of disk A. If the two disks stick together, how does the total angular momentum and total kinetic energy of the two-disk system after the disks are stuck together compare to that of the system before disk BB was dropped?

Total Angular Momentum: Remains the same Total Kenetic Energy: Is one half of its original value

An object is subject to multiple forces that result in the object having horizontal and vertical velocity components vx and vy, respectively as a function of time, as shown. Which of the following free-body diagrams could represent the forces exerted on the object?

dot in center with arrows pointing up to the right and on an angle down to the left