Weird stuff

The force F exerted on a ball during a collision with a wall is given as a function of time t by the equation F(t) = αt - βt 2 , where α = 400 N/s and β = 4000 N/s 2 . The ball first contacts the wall at t = 0, and the collision lasts for 0.10 s. What is the magnitude of the change in momentum of the ball? A 0 B 0.67 kg•m/s C 3.33 kg•m/s D 3.60 kg•m/s E The change in momentum of the ball cannot be determined without knowing the mass of the ball.

0.67 kg•m/s

A 5 kg object is propelled from rest at time t = 0 by a net force F that always acts in the same direction. The magnitude of F in newtons is given as a function of t in seconds by F = 0.5t. What is the speed of the object at t = 4 s? A 0.5 m/s B 0.8 m/s C 2.0 m/s D 4.0 m/s E 8.0 m/s

0.8 m/s

Three objects are located along the x-axis as shown above. The center of mass of the objects is at x = A 1.0 m B 1.5 m C 2.0 m D 2.5 m E 3.0 m

2.5 m

The momentum p of a moving object as a function of time t is given by the expression p = kt3, where k is a constant. The force causing this motion is given by the expression 3kt^2 3kt^2/2 kt^2/3 kt^4 kt^4/4

3kt^2

Two pucks moving on a frictionless air table are about to collide, as shown above. The 1.5 kg puck is moving directly east at 2.0 m/s. The 4.0 kg puck is moving directly north at 1.0 m/s. What is the magnitude of the total momentum of the two-puck system after the collision? A 1.0 kg⋅m/s B 3.5 kg⋅m/s C 5.0kg⋅m/s D 7.0kg⋅m/s E 5.55√kg⋅m/s

5.0kg*m/s

A 0.060 kg tennis ball moving at 15 m/s strikes a tennis racket and rebounds at 10 m/s in the opposite direction, as shown above. The ball is in contact with the racket for 0.030 s. What is the magnitude of the average force exerted by the racket on the ball? A 5 N B 10 N C 20 N D 25 N E 50 N

50 N

A person holds a portable fire extinguisher that ejects 1.0 kg of water per second horizontally at a speed of 6.0 m/s. What horizontal force in newtons must the person exert on the extinguisher in order to prevent it from accelerating? A 0 N B 6 N C 10 N D 18 N E 36 N

6 N

A 5-kilogram sphere is connected to a 10-kilogram sphere by a rigid rod of negligible mass, as shown above. Which of the five lettered points represents the center of mass of the sphere-rod combination? A B C D E

B

A 0.5 kg rubber ball initially moves with a speed of 10 m/s in the +x direction toward a stationary wall, as shown above. The ball bounces back off of the wall with a speed of 5 m/s in the −x direction. Which of the following best represents the rate of change of the ball's momentum dp/dt as a function of time?

B Triangle downward

Two balls are on a frictionless horizontal tabletop. Ball X initially moves at 10 meters per second, as shown in Figure I above. It then collides elastically with identical ball Y, which is initially at rest. After the collision, ball X moves at 6 meters per second along a path at 53° to its original direction, as shown in Figure II above. Which of the following diagrams best represents the motion of ball Y after the collision?

D 37, 8 m/s

A 2 kg ball collides with the floor at an angle 𝜽 and rebounds at the same angle and speed as shown above. Which of the following vectors represents the impulse exerted on the ball by the floor?

E Upward arrow

The uniform rod of length L shown above is supported by holding end X so that the rod makes an angle 60° with the horizontal floor. There is no friction acting between the rod and the floor. When the support at X is removed, the rod falls under the influence of gravity. Which of the following best describes the movement of end Y as the rod falls? It moves 1/2L to the left. A It remains at rest. B It moves 1/4L to the right. C It moves 1/2L to the right. D It moves 3/4L to the right.

It moves 1/4L to the right.

An object moving on a horizontal, frictionless surface makes a glancing collision with another object initially at rest on the surface. In this case which of the following is true about momentum and kinetic energy? Momentum is always conserved, and kinetic energy may be conserved. A Kinetic energy is always conserved, and momentum may be conserved. B Momentum is always conserved, and kinetic energy is never conserved. C Both momentum and kinetic energy are always conserved. D Neither momentum nor kinetic energy is conserved. E

Momentum is always conserved, and kinetic energy may be conserved.

A toy spacecraft is launched directly upward. When the toy reaches its highest point, a spring is released and the toy splits into two parts with masses of 0.02 kg and 0.08 kg, respectively. Immediately after the separation, the 0.02 kg part moves horizontally due east. Air resistance is negligible. True statements about the 0.08 kg part include which of the following? I. It could move north immediately after the spring is released. II. It takes longer to reach the ground than does the 0.02 kg part. III. It strikes the ground farther from the launch point than does the 0.02 kg part. None I only III only I and II only II and III only

None

Two balls, A and B, have the same mass and diameter but are made from different types of rubber. The balls are dropped from the same height above the floor. After colliding with the floor, ball A bounces higher than ball B bounces. Which of the following quantities must necessarily be larger for ball A than for ball B? A The average force exerted by the floor B The amount of time in contact with the floor C The impulse exerted by the floor D The momentum just before colliding with the floor E The kinetic energy just before colliding with the floor

The impulse exerted by the floor

Object A has a mass of M and is moving in the +x direction. It collides with object B , which has a mass of 2M and is initially at rest. After the collision, object B has a final velocity of v in the +x direction. Which of the following best describes the impulse object B exerts on object A during the collision? A −2Mv B −Mv C 0 D +Mv E +2Mv

−2Mv

Three objects of mass m, 2m, and 3m are at positions (0,0), (2,3), and (4,0), respectively, as shown above. The center of mass is located at position (8/3,1) (1,8/3) (16,6) (8,2) (1,1/2)

(8/3,1)

A person of mass 3M is standing on the left edge of a long, uniform board of mass M and length L that is floating in water, as shown in the figure above. The person walks slowly to the right edge of the board. The water exerts no drag forces on the board. The position of the center of mass of the board when the person is at the right edge of the board is 5L/4 3L/4 L/4 0 −L/4

-L/4

The graph above shows the force on an object of mass M as a function of time. For the time interval 0 to 4 s, the total change in the momentum of the object is A 40 kg•m/s B 20 kg•m/s C 0 kg•m/s D -20 kg•m/s E indeterminable unless the mass M of the object is known

0 kg*m/s

An object having an initial momentum that may be represented by the vector above strikes an object that is initially at rest. Which of the following sets of vectors may represent the momenta of the two objects after the collision?

E The answer looks like a "<"

A large truck of mass 4M is traveling at a speed of V when it collides with a small car of mass MM that is at rest. The truck and car stick together after the collision. During the collision, the car and truck exert forces on each other. Which of the following is a correct statement about these forces and gives evidence to support this statement? The forces the truck and car exert on each other must be external to the truck-car system because the momentum of the truck changes. The forces the truck and car exert on each other must be external to the truck-car system because the momentum of the car changes. The forces the truck and car exert on each other must be external to the truck-car system because the momentum of both the truck and car change. The forces the truck and car exert on each other must be internal to the truck-car system because the momentum of the center of mass of the truck-car system stays the same. The forces the truck and car exert on each other must be internal to the truck-car system because the momentum of the center of mass of the truck-car system changes.

The forces the truck and car exert on each other must be internal to the truck-car system because the momentum of the center of mass of the truck-car system stays the same.

The sum of all the external forces on a system of particles is zero. Which of the following must be true of the system? The total mechanical energy is constant. A The total potential energy is constant. B The total kinetic energy is constant. C The total linear momentum is constant. D It is in static equilibrium.

The total linear momentum is constant.

A particle of mass m starts from rest at position x = 0 and time t = 0. It moves along the positive x-axis under the influence of a single force Fx = bt , where b is a constant. The velocity v of the particle is given by bt/m bt^2/2m bt^2/m bsqrt(t)/m b/mt

bt^2/2m

Two small spheres are at rest on the x-axis of the coordinate system shown above. Sphere A of mass m1 is located at position x=d1. Sphere B of mass m2, where m1≠m2, is a distance d2 to the right of sphere A. Which of the following is a correct expression for the location of the center of mass for the two-sphere system? m2d2/m1+m2 d1 + m1d2/m1+m2 d2 + m1d1/m1+m2 m1d1 + m2d2/m1+m2 d1 + m2d2/m1+m2

d1 + m2d2/m1 + m2

A ball of mass m falls vertically, hits the floor with a speed vi , and rebounds with a speed vf . What is the magnitude of the impulse exerted on the ball by the floor? A 2m( vf - vi ) B m( vf - vi ) C m( vf + vi ) D mvi E mvf

m( vf + vi )

Blocks A, B, and C are aligned along a straight line on a horizontal frictionless surface. The masses of the blocks are M, 2M, and 3M, respectively. Block A is initially moving to the right along the same line at a speed v, as shown in the figure above. Blocks B and C are initially at rest. Block A collides with and sticks to block B. The two blocks then collide with and stick to block C. What is the speed of block C after the collisions? 0 A v/6 B v/3 C v/2 D 6v

v/6

A toy cannon is fixed to a small cart and both move to the right with speed v along a straight track, as shown above. The cannon points in the direction of motion. When the cannon fires a projectile the cart and cannon are brought to rest. If M is the mass of the cart and cannon combined without the projectile, and m is the mass of the projectile, what is the speed of the projectile relative to the ground immediately after it is fired? Mv/m (M+m)v/m (M-m)v/m mv/(M) mv/(M-m)

(M+m)v/m

Three identical spheres are thrown from the same height above the ground. Sphere X is thrown vertically up, sphere Y is thrown horizontally, and sphere Z is thrown vertically down, as shown in figures 1, 2, and 3 above, respectively. All three spheres are thrown with the same speed. Air resistance is negligible. Assume the spheres collide elastically with the ground. Which of the following ranks the spheres based on the rebound height after they collide with the ground? X > Y >Z Y > (X = Z) Z > Y > X ( X = Z) > Y (X = Z) > Y

(x = z) > y

In order to model the motion of an extinct ape, scientists measure its hand and arm bones. From shoulder to wrist, the arm bones are 0.60 m long and their mass is 4.0 kg. From wrist to the tip of the fingers, the hand bones are 0.10 m long and their mass is 1.0 kg. In the model above, each bone is assumed to have uniform density. When the arm and hand hang straight down, the distance from the shoulder to the center of mass of the arm-hand system is most nearly A 0.25 m B 0.35 m C 0.37 m D 0.50 m E 0.93 m

0.37 m

A railroad car of mass 1500 kg rolls to the right at 4 m/s and collides with another railroad car of mass 3000 kg that is rolling to the left at 3 m/s. The cars stick together. Their speed immediately after the collision is 2/3 m/s A 1 m/s B 5/3 m/s C 10/3 m/s D 7 m/s E

2/3 m/s

A person is standing at one end of a uniform raft of length L that is floating motionless on water, as shown above. The center of mass of the person-raft system is a distance d from the center of the raft. The person then walks to the other end of the raft. If friction between the raft and the water is negligible, how far does the raft move relative to the water? A L/2 B L C d/2 D d E 2d

2d

As shown in the top view above, a disc of mass m is moving horizontally to the right with speed v on a table with negligible friction when it collides with a second disc of mass 2m. The second disc is moving horizontally to the right with speed v/2 at the moment of impact. The two discs stick together upon impact. The speed of the composite body immediately after the collision is v/3 v/2 2v/3 3v/2 2v

2v/3

Object A of mass M is moving east at speed v. It collides with object B of mass 2M that was initially at rest. The motion of the objects before and after the collision is along the same line. After the collision, object A is moving west at a speed of v/3. What is the speed of object B immediately after the collision? v/3 A v/2 B 2v/3 C v D 2v E

2v/3

An object of mass m is moving with speed v0 to the right on a horizontal frictionless surface, as shown above, when it explodes into two pieces. Subsequently, one piece of mass 2/5 m moves with a speed v0/2 to the left. The speed of the other piece of the object is v0/2 v0/3 7v0/5 3v0/2 2v0

2v0

As shown in the figure above, a child of mass 20 kg who is running at a speed of 4.0 m/s jumps onto a stationary sled of mass 5.0 kg on a frozen lake. The speed at which the child and sled begin to slide across the ice is most nearly 0.20 m/s A 0.80 m/s B 1.2 m/s C 3.2 m/s D 16 m/s

3.2 m/s

The momentum p of a moving object as a function of time t is given by the expression p = kt3, where k is a constant. The force causing this motion is given by the expression A 3kt^2 B 3kt^2/2 C kt^2/3 D kt^4 E kt^4/4

3kt^2

A firecracker of mass 2m is moving at a speed v in the positive x-direction. It explodes and breaks up into two identical fragments, each of mass m. After the explosion, one fragment moves at the same speed v but in the negative x-direction. The speed of the second fragment must be v 2v 3v 4v 5v

3v

A large truck of mass 4M is traveling at a speed of V when it collides with a small car of mass M that is at rest. The truck and car stick together after the collision. The speed of the center of mass of the truck-car system as the truck and car move off together is 1/5V A 4/5V B V C 5/4V D 5V E

4/5V

A block of mass 3 kg, initially at rest, is pulled along a frictionless, horizontal surface with a force shown as a function of time t by the graph above. The speed of the block at t = 2s is A 4/3 m/s B 8/3 m/s C 4 m/s D 8 m/s E 24 m/s

4/3 m/s

A moon of mass m orbits a planet of mass 49m in an elliptical orbit as shown above. When the moon is at point A, its distance from the center of the planet is rA and its speed is v0. When the moon is at point B, its speed is 5v0. When the moon is at point A, the distance from the moon to the center of mass of the planet-moon system is most nearly 1/50rA 1/7rA 1/2rA 6/7rA 49/50rA

49/50rA

A ball initially moves horizontally with velocity vi , as shown above. It is then struck by a stick. After leaving the stick, the ball moves vertically with a velocity v𝑓 , which is smaller in magnitude than vi . Which of the following vectors best represents the direction of the average force that the stick exerts on the ball?

B Arrow top left

A ball of mass m and velocity v contacts a hard surface at a 45° angle and bounces off the surface also at a 45° angle and at speed v, as shown in situation 1. Also shown is the force vector F⃗ representing the force exerted by the surface on the ball. Situation 2 shows the same ball moving with the same velocity and contacts a soft surface. The time of contact is greater with the soft surface than the hard surface. The ball bounces off the soft surface at an angle of 30° and with speed v2<v. Which of the following vectors could represent the force exerted on the ball in situation 2.

C The arrow pointing top-right

Data were collected during an experiment that used two identical cars, car 1 and car 2, moving along a one-dimensional track. Car 1 moved toward and collided with stationary car 2, and data were collected. The data collected just before and just after the collision are shown below. (All velocities are represented in m/s .) What conclusion can be made about the data taken in this experiment? Car 1 was more massive than car 2. Car 2 was more massive than car 1. The velocity measurements for car 1 were lower than the car's actual speed. The velocity measurements for car 2 were higher than the car's actual speed. The experiment was performed without error.

Car 2 was more massive than car 1.

Two balls with masses m and 2m approach each other with equal speeds v on a horizontal frictionless table, as shown in the top view above. Which of the following shows possible velocities of the balls for a time soon after the balls collide?

D check file explorer

A balloon of mass M is floating motionless in the air. A person of mass less than M is on a rope ladder hanging from the balloon. The person begins to climb the ladder at a uniform speed v relative to the ground. How does the balloon move relative to the ground? A)Up with speed v B)Up with a speed less than v C)Down with speed v D)Down with a speed less than v E)The balloon does not move.

Down with a speed less than v

Three identical disks are initially at rest on a frictionless, horizontal table with their edges touching to form a triangle, as shown in the top view above. An explosion occurs within the triangle, propelling the disks horizontally along the surface. Which of the following diagrams shows a possible position of the disks at a later time? (In these diagrams, the triangle is shown in its original position.)

E

In an experiment, students use a force sensor to apply a force of magnitude F to an object of mass m that is initially at rest. The force is exerted in the +x-direction for a time t=T. The impulse exerted on the device is J. Which of following procedure changes would result in an impulse 2J being exerted on an object? A Exert a force of magnitude F2 on an object of mass mm for a time t=T. B Exert a force of magnitude F/2 on an object of mass 2m for a time t=2T. C Exert a force of magnitude F on an object of mass 2m for a time t=2T. D Exert a force of magnitude 2F on an object of mass mm for a time t=2T. E Exert a force of magnitude 2F on an object of mass mm for a time t=T/2

Exert a force of magnitude F on an object of mass 2m for a time t=2T.

Identical blocks 11 and 22 slide on a horizontal surface toward a stationary barrier. At time t=0t=0, block 11 collides with the barrier and slides backward. The blocks collide at time t=Δtt=Δt. Assuming friction between the blocks and the horizontal surface to be negligible, which of the following statements is true about the two blocks? If the collision between block 11 and the wall is elastic, and the two blocks have an elastic collision, then the sum of the kinetic energy of blocks 11 and 22 before block 11 makes contact with the wall will be equal to the sum of the kinetic energy of blocks 11 and 22 after the collision between the blocks. If the collision between block 11 and the wall is elastic, and the two blocks have an inelastic collision, then the sum of the kinetic energy of blocks 11 and 22 before block 11 makes contact with the wall will be equal to the sum of the kinetic energy of blocks 11 and 22 after the collision between the blocks. If the collision between block 11 and the wall is not elastic, and the two blocks have an inelastic collision, then the sum of the kinetic energy of blocks 11 and 22 before block 11 makes contact with the wall will be less than the sum of the kinetic energy of blocks 11 and 22 after the collision between the blocks If the collision between block 11 and the wall is not elastic, and the two blocks have an inelastic collision, then the momentum of block 11 before it makes contact with the wall will be equal to the sum of the momenta of the two blocks after the collision between the blocks. If the collision between block 11 and the wall is not elastic, and the two blocks have an inelastic collision, then the momentum of block 11 before it makes contact with the wall will be equal to the sum of the momenta of the two blocks after the collision between the blocks.

If the collision between block 1 and the wall is elastic, and the two blocks have an elastic collision, then the sum of the kinetic energy of blocks 1 and 2 before block 1 makes contact with the wall will be equal to the sum of the kinetic energy of blocks 1 and 2 after the collision between the blocks.

Object X of mass m is moving to the right with a speed of 3 m/s when it collides with object Y of mass m that is moving to the right with a speed of 2 m/s, as shown above. After the collision, X is moving to the right with a speed of 2 m/s and Y is moving to the right with a speed of 3 m/s. Which of the following is true of the collision? It is elastic because momentum is conserved. A It is elastic because kinetic energy is conserved. B It is inelastic because momentum is not conserved. C It is inelastic because kinetic energy is not conserved. D More information is needed to determine whether the collision is elastic or inelastic.

It is elastic because kinetic energy is conserved.

Identical net forces act for the same length of time on two different spherical masses. Which of the following describes the change in linear momentum of the smaller mass compared to that of the larger mass? A It is smaller than the change in linear momentum of the larger mass but not zero. B It is larger than the change in linear momentum of the larger mass. C It is equal to the change in linear momentum of the larger mass. D It is zero. E It depends on the relative diameters of the two masses.

It is equal to the change in linear momentum of the larger mass.

Two spheres of uniform density are located a distance L apart, as shown in the figure below. The left sphere has a mass M 1 , and the right sphere has a mass M 2 . The center of mass of the two spheres is labeled point P. Which of the following is a correct expression for the distance from point P to the center of the left sphere? M1/M2*L (M1+M2)/M1*L (M1+M2)/M2*L M2/(M1+M2)*L M1/(M1+M2)*L

M2/(M1+M2)*L

Which of the following is equivalent to a unit of momentum? A Joule B Newton C Joule • second D Newton • second E Newton • meter

Newton * second

In an experiment, students use motion sensors to measure the speed of objects 1 and 2, of masses m1 and m2, respectively, that collide head-on while moving along a smooth horizontal surface. Consider velocity to the right to be positive. All motion is along a straight line. The speeds of object 1 are v1i before the collision and v1f after the collision. The speeds of object 2 are v2i before the collision and v2f after the collision. Before the collisions, object 1 is moving to the right and and object 2 is moving to the left. Both objects reverse their direction of motion during the collision, as shown. After analyzing the data, a student noticed that the motion sensor measuring the velocity of object 2 was not facing directly along the line of motion of object 2, but was angled slightly. How would this affect the data collected by the students? The actual speeds of object 2 are smaller in magnitude both before and after the collision. A The actual speeds of object 2 are larger in magnitude both before and after the collision. B There is no effect on the data C The actual speeds of object 2 are smaller in magnitude before and larger in magnitude after the collision. D The actual speeds of object 2 are larger in magnitude before and smaller in magnitude after the collision. E

The actual speeds of object 2 are larger in magnitude both before and after the collision.

For an impulse-momentum experiment, students collect data on a collision between blocks A and B. A force probe attached to block A is used to measure the force exerted by block A on block B as a function of time during the collision. The data collected shows a positive force that is used to determine the impulse on block B. The force sensor is removed from block A and attached to block B, and the experiment is run again. Which of the following correctly describes how this affects the data and if the impulse on block B can still be determined? A The data can only be used to determine the impulse on block AA, not block BB . B The data can only be used to determine the impulse on block BB, not block AA. C The data cannot be used to determine the impulse on block AA or block BB. D The data can be used to determine the impulse on block BB and block AA. E The data can be used to determine the force on block BB. Answer A

The data can be used to determine the impulse on block B and block A.

In an experiment, block 1 is given an initial speed v0 toward block 2, which is initially at rest. The blocks are on a track that has a motion detector set up, as shown above. When the two blocks collide, there is a completely inelastic collision and the blocks move together with speed vf. The blocks were both placed on a balance, and it is determined that they have the same mass. The experiment is repeated for four different initial speeds, and the data are shown in the chart below. It appears that the resulting data are not accurate. Which measurement most likely produced errors in the data seen in the chart below? The mass of block 1 is accurate, but the mass of block 2 is actually less massive than recorded. Both mass values are accurate, but v0 is actually larger than recorded. The motion sensor was positioned too close to block 1. The final velocity recorded was taken too long after the collision. The data recorded is accurate within acceptable experimental error.

The final velocity recorded was taken too long after the collision.

The graph of velocity as a function of time shown above is for a 10 kg box moving along the x-axis. Based on the graph, which of the following is a true statement? A The linear momentum of the box is constant over the entire time frame. B The linear momentum of the box is only constant between 2 and 5 seconds. C The linear momentum of the box is constant between 0 and 2 seconds. D The maximum linear momentum of the box is 7kg⋅m/s E The minimum linear momentum of the box is 40kg⋅m/s

The linear momentum of the box is only constant between 2 and 5 seconds.

The graph of velocity as a function of time shown above is for a 10 kg box moving along the x-axis. Based on the graph, which of the following is a true statement? A The linear momentum of the box is constant over the entire time frame. B The linear momentum of the box is only constant between 2 and 5 seconds. C The linear momentum of the box is constant between 00 and 22 seconds. D The maximum linear momentum of the box is 7kg⋅m/s7kg⋅m/s. E The minimum linear momentum of the box is 40kg⋅m/s40kg⋅m/s.

The linear momentum of the box is only constant between 2 and 5 seconds.

In an experiment to study collisions, block A with of mass m1 is moving speed v0 when it collides with block B of mass m2 which is initially at rest. After the collision, the blocks stick together and move off with speed vf. For a series of collisions, block A is given different initial velocities. The graph of vf as a function of v0 is shown. How would doubling mass m1 change the graph? The slope of the graph line would be less. A The slope of the graph line would be greater. B The graph line would no longer be linear. C There would be no effect on the graph. D The change cannot be determined without knowing the ratio of m1/m2. E

The slope of the graph line would be greater.

A large truck of mass 4M is traveling at a speed of V when it collides with a small car of mass M that is at rest. The truck and car stick together after the collision. When the truck and car stuck together after the collision, the speed of the center of mass of the truck-car system is Vf. If the truck and car have an elastic collision, the speed of the center of mass of the truck-car system is Vf2. Which of the following expressions for Vf2 must be true? Vf2>2Vf A Vf<Vf2<2Vf B Vf2=Vf C 1/2Vf<Vf2<Vf D Vf2<1/2Vf E

Vf2=Vf

Two blocks of masses M and 2M are on a frictionless horizontal surface, as shown above, and are held in place with a compressed spring of negligible mass between them. If the blocks are then released and the block of mass 2M leaves the spring with a velocity v, the velocity of the center of mass of the blocks is zero A −v/2 B −2v/3 C −3v/2 D −2v

Zero

Two people are initially standing still on frictionless ice. They push on each other so that one person, of mass 120 kg, moves to the left at 2 m/s, while the other person, of mass 80 kg, moves to the right at 3 m/s. What is the velocity of their center of mass? Zero A 0.5 m/s to the left B 1 m/s to the right C 2.4 m/s to the left D 2.5 m/s to the right

Zero

Objects 1 and 2 have the same momentum. Object 1 can have more kinetic energy than object 2 if, compared with object 2, it A has more mass B has the same mass C is moving at the same speed D is moving slower E is moving faster

is moving faster

In an experiment, students use motion sensors to measure the speed of objects 1 and 2, of masses m1 and m2, respectively, that collide head-on while moving along a smooth horizontal surface. Consider velocity to the right to be positive. All motion is along a straight line. The speeds of object 1 are v1i before the collision and v1f after the collision. The speeds of object 2 are v2i before the collision and v2f after the collision. Before the collisions, object 1 is moving to the right and and object 2 is moving to the left. Both objects reverse their direction of motion during the collision, as shown. Which of the following expressions can be used to determine the magnitude of the impulse on object 1 ? A m2(v2f−v2i) B m1(v2f−v2i) C m2(v1f−v1i)

m2(v2f−v2i)

Particle A and particle B, each of mass M, move along the x-axis exerting a force on each other. The potential energy of the system of two particles associated with the force is given by the equation U = β / r 2 , where r is the distance between the two particles and β is a positive constant. At time t = 0, particle A is located at x = 2D with an initial speed of v0 to the left, and particle B is at rest at the origin, as shown in the figure above. At time t = T1, particle A is observed to be traveling with speed 2v0 / 3 to the left. The speed and direction of motion of particle B is 2v0/3 to the left A v0/3 to the left B v0/3 to the right C 2v0/3 to the right D 5v0/3 to the left E

v0/3 to the left

A student drops a bag of mass m onto a cart of mass M that is sliding with speed v0 along a horizontal track with negligible friction. Immediately after the bag lands in the cart, the cart-bag system moves with speed vf. Which of the following statements correctly relates the two speeds and gives a correct reason for this relationship? vf<v0, because some of the cart-bag system's mechanical energy is dissipated. A vf<v0, because the kinetic energy of the bag decreases. B vf>v0, because the kinetic energy of the bag decreases. C vf>v0, because the linear momentum of the bag is added to the linear momentum of the cart. D vf=v0, because the bag is moving perpendicular to the cart. E

vf<v0, because some of the cart-bag system's mechanical energy is dissipated.