Question 1

Two objects of different mass have equal,non-zero kinetic energies.Which object has the greater magnitude momentum?

Accepted Answer

A) the heavier object 
B) the lighter object 
C) They both have the same magnitude momentum. 
A) the heavier object 
B) the lighter object 
C) They both have the same magnitude momentum.

Question 2

A 0.14-kg baseball is dropped from rest from a height of 2.0 m above the ground.What is the magnitude of its momentum just before it hits the ground if we neglect air resistance?

Accepted Answer

A) 0.28 kg ∙ m/s 
B) 0.88 kg ∙ m/s 
C) 0.44 kg ∙ m/s 
D) 0.62 kg ∙ m/s 
E) 1.4 kg ∙ m/s 
A) 0.28 kg ∙ m/s 
B) 0.88 kg ∙ m/s 
C) 0.44 kg ∙ m/s 
D) 0.62 kg ∙ m/s 
E) 1.4 kg ∙ m/s

Question 3

A 600-kg car makes a 90° turn.Its speed before the turn is 21.0 m/s and after the turn it is 24.0 m/s.What is the magnitude of the change in the car's momentum during the turn?

Accepted Answer

A) 19.1 × 1   kg∙m/s 
B) 10.2 × 1   kg∙m/s 
C) 9.55 × 1   kg∙m/s 
D) 12.0 × 1   kg∙m/s 
E) 22.2 × 1   kg∙m/s 
A) 19.1 × 1   kg∙m/s 
B) 10.2 × 1   kg∙m/s 
C) 9.55 × 1   kg∙m/s 
D) 12.0 × 1   kg∙m/s 
E) 22.2 × 1   kg∙m/s

Question 4

In a certain nuclear reactor,neutrons suddenly collide with deuterons,which have twice the mass of neutrons.In a head-on elastic collision with a stationary deuteron,what fraction of the initial kinetic energy of a neutron is transferred to the deuteron?

Accepted Answer

A) 1/2 
B) 1/3 
C) 3/4 
D) 5/6 
E) 8/9 
A) 1/2 
B) 1/3 
C) 3/4 
D) 5/6 
E) 8/9

Question 5

Identical forces act for the same length of time on two different objects.The magnitude of the change in momentum of the lighter object is

Accepted Answer

A) smaller than the magnitude of the change in momentum of the larger mass,but not zero. 
B) larger than the magnitude of the change in momentum of the larger mass. 
C) exactly equal to the magnitude of the change in momentum of the larger mass. 
D) zero. 
E) There is not enough information to answer the question. 
A) smaller than the magnitude of the change in momentum of the larger mass,but not zero. 
B) larger than the magnitude of the change in momentum of the larger mass. 
C) exactly equal to the magnitude of the change in momentum of the larger mass. 
D) zero. 
E) There is not enough information to answer the question.

Question 6

Three masses,1.0 kg,2.0 kg,and 3.0 kg,are located at (0.0 m,0.0 m),(1.0 m,1.0 m),and (2.0 m,-2.0 m),respectively.What is the location of the center of mass (or center of gravity)of this system?

Accepted Answer

A) (1.3 m,0.67 m) 
B) (1.3 m,-0.67 m) 
C) (-1.3 m,0.67 m) 
D) (-1.3 m,-0.67 m) 
A) (1.3 m,0.67 m) 
B) (1.3 m,-0.67 m) 
C) (-1.3 m,0.67 m) 
D) (-1.3 m,-0.67 m)

Question 7

A 320-g air track cart traveling at 1.25 m/s suddenly collides elastically with a stationary 270-g cart.What is the speed of the 320-g cart just after the collision?

Accepted Answer

A) 0.68 m/s 
B) 0.11 m/s 
C) 0.21 m/s 
D) 1.4 m/s 
E) 1.1 m/s 
A) 0.68 m/s 
B) 0.11 m/s 
C) 0.21 m/s 
D) 1.4 m/s 
E) 1.1 m/s

Question 8

A 0.10-kg ball,traveling horizontally at 25 m/s,strikes a wall and rebounds at 19 m/s.What is the magnitude of the change in the momentum of the ball during the rebound?

Accepted Answer

A) 1.2 kg ∙ m/s 
B) 1.8 kg ∙ m/s 
C) 4.4 kg ∙ m/s 
D) 5.4 kg ∙ m/s 
E) 72 kg ∙ m/s 
A) 1.2 kg ∙ m/s 
B) 1.8 kg ∙ m/s 
C) 4.4 kg ∙ m/s 
D) 5.4 kg ∙ m/s 
E) 72 kg ∙ m/s

Question 9

A steady horizontal force lasting for 2.1 s gives a 1.25 kg object an acceleration of 3.2 m/s2 on a frictionless table.What impulse does this force give to the object?

Accepted Answer

A) 26 kg ∙ m/s 
B) 11 kg ∙ m/s 
C) 8.4 kg ∙ m/s 
D) 2.6 kg ∙ m/s 
A) 26 kg ∙ m/s 
B) 11 kg ∙ m/s 
C) 8.4 kg ∙ m/s 
D) 2.6 kg ∙ m/s

Question 10

In the figure,four point masses are placed as shown.Assume that all the numbers in the figure are accurate to two significant figures.What are the x and y coordinates of the center of mass (or center of gravity)of this arrangement?

Accepted Answer

A) (2.2 m,2.6 m) 
B) (2.2 m,2.7 m) 
C) (2.3 m,2.6 m) 
D) (2.3 m,2.7 m) 
E) (2.3 m,2.8 m) 
A) (2.2 m,2.6 m) 
B) (2.2 m,2.7 m) 
C) (2.3 m,2.6 m) 
D) (2.3 m,2.7 m) 
E) (2.3 m,2.8 m)

Question 11

A golf ball of mass 0.050 kg is at rest on the tee.Just after being struck,it has a velocity of 102 m/s.If the club and ball were in contact for  
What is the average force exerted on the ball by the club?

Accepted Answer

A) 6.3 kN 
B) 7.1 kN 
C) 5.5 kN 
D) 4.9 kN 
A) 6.3 kN 
B) 7.1 kN 
C) 5.5 kN 
D) 4.9 kN

Question 12

A 60.0-kg man stands at one end of a 20.0-kg uniform 10.0-m long board.How far from the man is the center of mass (or center of gravity)of the man-board system?

Accepted Answer

A) 1.25 m 
B) 2.50 m 
C) 5.00 m 
D) 7.50 m 
E) 9.00 m 
A) 1.25 m 
B) 2.50 m 
C) 5.00 m 
D) 7.50 m 
E) 9.00 m

Question 13

In a police ballistics test,a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest.The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed.What is the speed of the block just after the bullet emerges?

Accepted Answer

A) 1.50 m/s 
B) 2.97 m/s 
C) 3.00 m/s 
D) 273 m/s 
A) 1.50 m/s 
B) 2.97 m/s 
C) 3.00 m/s 
D) 273 m/s

Question 14

Two air track carts move along an air track towards each other.Cart A has a mass of 450 g and moves toward the right with a speed of 0.850 m/s.Cart B has a mass of 300 g and moves toward the left with a speed of 1.12 m/s.What is the total momentum of the two-cart system?

Accepted Answer

A) 0.047 kg ∙ m/s toward the right 
B) 0.719 kg ∙ m/s toward the right 
C) 0.719 kg ∙ m/s toward the left 
D) 0.750 kg ∙ m/s toward the right 
E) 0.750 kg ∙ m/s toward the left 
A) 0.047 kg ∙ m/s toward the right 
B) 0.719 kg ∙ m/s toward the right 
C) 0.719 kg ∙ m/s toward the left 
D) 0.750 kg ∙ m/s toward the right 
E) 0.750 kg ∙ m/s toward the left

Question 15

A rocket explodes into two fragments,one 25 times heavier than the other.The magnitude of the momentum change of the lighter fragment is

Accepted Answer

A) 25 times as great as the momentum change of the heavier fragment. 
B) The same as the momentum change of the heavier fragment. 
C) 1/25 as great as the momentum change of the heavier fragment. 
D) 5 times as great as the momentum change of the heavier fragment. 
E) 1/4 as great as the momentum change of the heavier fragment. 
A) 25 times as great as the momentum change of the heavier fragment. 
B) The same as the momentum change of the heavier fragment. 
C) 1/25 as great as the momentum change of the heavier fragment. 
D) 5 times as great as the momentum change of the heavier fragment. 
E) 1/4 as great as the momentum change of the heavier fragment.

Question 16

In the figure showing an isolated system,determine the character of the collision.The masses of the blocks,and the velocities before and after,are shown.The collision is

Accepted Answer

A) perfectly elastic. 
B) partially inelastic. 
C) completely inelastic. 
D) characterized by an increase in kinetic energy. 
E) not possible because momentum is not conserved. 
A) perfectly elastic. 
B) partially inelastic. 
C) completely inelastic. 
D) characterized by an increase in kinetic energy. 
E) not possible because momentum is not conserved.

Question 17

A 2.0-m rope is lying on a table.You pick up one end and start raising it vertically.How high above the table is the center of mass (or center of gravity)of the rope when half of the rope has lifted off the table?

Accepted Answer

A) 0.25 m 
B) 0.50 m 
C) 0.75 m 
D) 1.0 m 
E) 1.5 m 
A) 0.25 m 
B) 0.50 m 
C) 0.75 m 
D) 1.0 m 
E) 1.5 m

Question 18

Which of the following quantities are units of momentum? (There could be more than one correct choice. )

Accepted Answer

A) N ∙ m 
B) kg ∙ s/m 
C) kg ∙ m/s 
D) N ∙ s 
E) kg ∙ m2/s2 
A) N ∙ m 
B) kg ∙ s/m 
C) kg ∙ m/s 
D) N ∙ s 
E) kg ∙ m2/s2

Question 19

A block of mass m = 34 kg and speed V is behind a block of mass M = 81 kg and speed of  
As shown in the figure.The surface is frictionless and the blocks collide and couple.After the collision,the blocks have a common speed of  
What is the magnitude of the impulse on the 34-kg block due to the collision?

Accepted Answer

A) 32 N ∙ s 
B) 14 N ∙ s 
C) 41 N ∙ s 
D) 57 N ∙ s 
E) 73 N ∙ s 
A) 32 N ∙ s 
B) 14 N ∙ s 
C) 41 N ∙ s 
D) 57 N ∙ s 
E) 73 N ∙ s

Question 20

Calculate the impulse due to a force of  
That lasts for

Accepted Answer

A) 6.3 kg∙ m/s 
B) 5.0 kg∙ m/s 
C) 5.7 kg∙ m/s 
D) 6.9 kg∙ m/s 
A) 6.3 kg∙ m/s 
B) 5.0 kg∙ m/s 
C) 5.7 kg∙ m/s 
D) 6.9 kg∙ m/s

Exam 9: Linear Momentum and Collisions

Two objects of different mass have equal,non-zero kinetic energies.Which object has the greater magnitude momentum?

A 0.14-kg baseball is dropped from rest from a height of 2.0 m above the ground.What is the magnitude of its momentum just before it hits the ground if we neglect air resistance?

A 600-kg car makes a 90° turn.Its speed before the turn is 21.0 m/s and after the turn it is 24.0 m/s.What is the magnitude of the change in the car's momentum during the turn?

In a certain nuclear reactor,neutrons suddenly collide with deuterons,which have twice the mass of neutrons.In a head-on elastic collision with a stationary deuteron,what fraction of the initial kinetic energy of a neutron is transferred to the deuteron?

Identical forces act for the same length of time on two different objects.The magnitude of the change in momentum of the lighter object is

Three masses,1.0 kg,2.0 kg,and 3.0 kg,are located at (0.0 m,0.0 m),(1.0 m,1.0 m),and (2.0 m,-2.0 m),respectively.What is the location of the center of mass (or center of gravity)of this system?

A 320-g air track cart traveling at 1.25 m/s suddenly collides elastically with a stationary 270-g cart.What is the speed of the 320-g cart just after the collision?

A 0.10-kg ball,traveling horizontally at 25 m/s,strikes a wall and rebounds at 19 m/s.What is the magnitude of the change in the momentum of the ball during the rebound?

A steady horizontal force lasting for 2.1 s gives a 1.25 kg object an acceleration of 3.2 m/s2 on a frictionless table.What impulse does this force give to the object?

In the figure,four point masses are placed as shown.Assume that all the numbers in the figure are accurate to two significant figures.What are the x and y coordinates of the center of mass (or center of gravity)of this arrangement?

A golf ball of mass 0.050 kg is at rest on the tee.Just after being struck,it has a velocity of 102 m/s.If the club and ball were in contact for What is the average force exerted on the ball by the club?

A 60.0-kg man stands at one end of a 20.0-kg uniform 10.0-m long board.How far from the man is the center of mass (or center of gravity)of the man-board system?

In a police ballistics test,a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest.The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed.What is the speed of the block just after the bullet emerges?

Two air track carts move along an air track towards each other.Cart A has a mass of 450 g and moves toward the right with a speed of 0.850 m/s.Cart B has a mass of 300 g and moves toward the left with a speed of 1.12 m/s.What is the total momentum of the two-cart system?

A rocket explodes into two fragments,one 25 times heavier than the other.The magnitude of the momentum change of the lighter fragment is

In the figure showing an isolated system,determine the character of the collision.The masses of the blocks,and the velocities before and after,are shown.The collision is

A 2.0-m rope is lying on a table.You pick up one end and start raising it vertically.How high above the table is the center of mass (or center of gravity)of the rope when half of the rope has lifted off the table?

Which of the following quantities are units of momentum? (There could be more than one correct choice. )

Calculate the impulse due to a force of That lasts for

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A steady horizontal force lasting for 2.1 s gives a 1.25 kg object an acceleration of 3.2 m/s² on a frictionless table.What impulse does this force give to the object?