Question 1

Two equal masses travel in opposite directions with equal speed.If they collide in a perfectly elastic collision,then,just after the collision,their velocities will be

Accepted Answer

A) zero. 
B) equal to their original velocities. 
C) equal in magnitude but opposite in direction to their original velocities. 
D) less in magnitude and in the same direction as their original velocities. 
E) less in magnitude and opposite in direction to their original velocities.

Question 2

A car having a total mass of 2250 kg and traveling at 72 km/h smashes into a tree.The car is stopped in 0.25 s.The driver of the car is not held in place by a seat belt or any other restraining device.Just after the impact but before the driver hits any part of the car,the acceleration of the driver is

Accepted Answer

A) 80 m/s2 toward the tree. 
B) zero with respect to the tree. 
C) 80 m/s2 away from the tree. 
D) 1.8 $\times$ 102m/s2 with respect to the car. 
E) 37 m/s2 away from the tree.

Question 3

A man in a spacecraft that is moving with a velocity V0 in free space runs forward and then stops.The center of mass of the system (that is,the ship and the man)

Accepted Answer

A) slows while the man is running,then speeds up when he stops. 
B) slows while the man is running,then resumes its original velocity when he stops. 
C) moves faster while the man is running,then slows when he stops. 
D) moves faster while the man is running,then resumes its original velocity when he stops. 
E) continues all the while at its original velocity.

Question 4

A superball of mass m is dropped vertically from a height,h.If the impact time with the floor is $\Delta$t,what is the average force on the ball? (Assume that the superball bounces back to the same height.)

Accepted Answer

A)   
B)   
C)   
D)   
E) none of the above

Question 5

Two bodies A and B move toward each other with speeds of 80 cm/s and 20 cm/s,respectively.The mass of A is 140 g and that of B is 60 g.After a head-on,perfectly elastic collision,the speed of B is

Accepted Answer

A) 8.0 cm/s 
B) 20 cm/s 
C) 92 cm/s 
D) 1.2 m/s 
E) 1.3 m/s

Question 6

You shoot an arrow with a mass of 0.54 kg at 45º above the horizontal.The bow exerts a force of 125 N for 0.65 s.With no air resistance,the maximum height the arrow reaches is

Accepted Answer

A) 1.2 km 
B) 5.4 m 
C) 0.57 km 
D) 0.29 km 
E) 0.61 km

Question 7

A bullet of mass m and velocity  strikes and becomes imbedded in a wooden block of mass M,which is initially at rest on a frictionless surface.The ratio of the velocity of the system after collision to the initial velocity of the bullet is

Accepted Answer

A) (M + m)/m 
B) (M + m)/M 
C) M/(m + M) 
D) m/(m + M) 
E) M/(m - M)

Question 8

While in horizontal flight at a speed of 20 m/s,a baseball of mass 0.11 kg is struck by a bat.After leaving the bat,the baseball has a speed of 29 m/s in a direction opposite to its original direction.The magnitude of the impulse given the ball is

Accepted Answer

A) 0.99 kg · m/s 
B) 5.4 kg · m/s 
C) 2.2 kg · m/s 
D) 3.2 kg · m/s 
E) 0.55 kg · m/s

Question 9

Consider an inelastic collision between balls of mass m1 and m2.The velocities before the collision are  1 and  2,respectively,and the velocities after the collision are  1 and  2,respectively.Which of the following statements concerning this collision is true?

Accepted Answer

A) m1     
1 + m1
    
1 = m2
    
2 + m2
    
2  
B)   2 -  1 >  1 -  2  
C)   2 -  1 =  1 -  2  
D)   2 -  1 1 -  2  
E)   m1(  1)2 +  m2(  2)2 =  m1(  1)2 +  m2(  2)2

Question 10

A block that has a mass M = 4.25 kg is hanging at rest on a light string.A projectile with a mass m = 250 g moving horizontally strikes M and sticks to it.The block and its projectile swing up and the center of mass rises a distance h = 12.0 cm.The speed of the projectile is approximately

Accepted Answer

A) 28 m/s 
B) 42 m/s 
C) 0.28 km/s 
D) 26 m/s 
E) 14 m/s

Question 11

In an elastic collision of two objects,

Accepted Answer

A) momentum is not conserved. 
B) momentum is conserved,and the kinetic energy after the collision is less than its value before the collision. 
C) momentum is conserved,and the kinetic energy after the collision is the same as the kinetic energy before the collision. 
D) momentum is not conserved,and the kinetic energy of the system after the collision differs from the kinetic energy of the system before the collision. 
E) the kinetic energy of the system after the collision depends on the masses of the objects.

Question 12

If you take the derivative of the kinetic energy of a particle with respect to its velocity,you get

Accepted Answer

A) force. 
B) momentum. 
C) acceleration. 
D) mass. 
E) potential energy.

Exam 8: Systems of Particles and Conservation of Linear Momentum

Two equal masses travel in opposite directions with equal speed.If they collide in a perfectly elastic collision,then,just after the collision,their velocities will be

A man in a spacecraft that is moving with a velocity V₀ in free space runs forward and then stops.The center of mass of the system (that is,the ship and the man)

A superball of mass m is dropped vertically from a height,h.If the impact time with the floor is $\Delta$ t,what is the average force on the ball? (Assume that the superball bounces back to the same height.)

Two bodies A and B move toward each other with speeds of 80 cm/s and 20 cm/s,respectively.The mass of A is 140 g and that of B is 60 g.After a head-on,perfectly elastic collision,the speed of B is

You shoot an arrow with a mass of 0.54 kg at 45º above the horizontal.The bow exerts a force of 125 N for 0.65 s.With no air resistance,the maximum height the arrow reaches is

A bullet of mass m and velocity strikes and becomes imbedded in a wooden block of mass M,which is initially at rest on a frictionless surface.The ratio of the velocity of the system after collision to the initial velocity of the bullet is

While in horizontal flight at a speed of 20 m/s,a baseball of mass 0.11 kg is struck by a bat.After leaving the bat,the baseball has a speed of 29 m/s in a direction opposite to its original direction.The magnitude of the impulse given the ball is

Consider an inelastic collision between balls of mass m₁ and m₂.The velocities before the collision are ₁ and ₂,respectively,and the velocities after the collision are ₁ and ₂,respectively.Which of the following statements concerning this collision is true?

A block that has a mass M = 4.25 kg is hanging at rest on a light string.A projectile with a mass m = 250 g moving horizontally strikes M and sticks to it.The block and its projectile swing up and the center of mass rises a distance h = 12.0 cm.The speed of the projectile is approximately

In an elastic collision of two objects,

If you take the derivative of the kinetic energy of a particle with respect to its velocity,you get

Exam 8: Systems of Particles and Conservation of Linear Momentum

Two equal masses travel in opposite directions with equal speed.If they collide in a perfectly elastic collision,then,just after the collision,their velocities will be

A man in a spacecraft that is moving with a velocity V0 in free space runs forward and then stops.The center of mass of the system (that is,the ship and the man)

A superball of mass m is dropped vertically from a height,h.If the impact time with the floor is Δ\DeltaΔ t,what is the average force on the ball? (Assume that the superball bounces back to the same height.)

Two bodies A and B move toward each other with speeds of 80 cm/s and 20 cm/s,respectively.The mass of A is 140 g and that of B is 60 g.After a head-on,perfectly elastic collision,the speed of B is

You shoot an arrow with a mass of 0.54 kg at 45º above the horizontal.The bow exerts a force of 125 N for 0.65 s.With no air resistance,the maximum height the arrow reaches is

A bullet of mass m and velocity strikes and becomes imbedded in a wooden block of mass M,which is initially at rest on a frictionless surface.The ratio of the velocity of the system after collision to the initial velocity of the bullet is

While in horizontal flight at a speed of 20 m/s,a baseball of mass 0.11 kg is struck by a bat.After leaving the bat,the baseball has a speed of 29 m/s in a direction opposite to its original direction.The magnitude of the impulse given the ball is

Consider an inelastic collision between balls of mass m1 and m2.The velocities before the collision are 1 and 2,respectively,and the velocities after the collision are 1 and 2,respectively.Which of the following statements concerning this collision is true?

A block that has a mass M = 4.25 kg is hanging at rest on a light string.A projectile with a mass m = 250 g moving horizontally strikes M and sticks to it.The block and its projectile swing up and the center of mass rises a distance h = 12.0 cm.The speed of the projectile is approximately

In an elastic collision of two objects,

If you take the derivative of the kinetic energy of a particle with respect to its velocity,you get

A man in a spacecraft that is moving with a velocity V₀ in free space runs forward and then stops.The center of mass of the system (that is,the ship and the man)

A superball of mass m is dropped vertically from a height,h.If the impact time with the floor is $\Delta$ t,what is the average force on the ball? (Assume that the superball bounces back to the same height.)

Consider an inelastic collision between balls of mass m₁ and m₂.The velocities before the collision are ₁ and ₂,respectively,and the velocities after the collision are ₁ and ₂,respectively.Which of the following statements concerning this collision is true?