Question 1

A ball of mass 0.40 kg is initially moving to the left at 30 m/s. After hitting a wall, it rebounds to the right at 20 m/s. What is the impulse delivered to the ball by the wall?

Accepted Answer

$$4.0\ \mathrm{kg\cdot m/s}$$\ to\ the\ right$

Question 2

A car is brought to rest from 90 km/h in two different ways: (i) by slamming into a wall, and (ii) by plowing into a giant tub of gelatin, coming to a gradual halt. In which case is the impulse of the net force on the car greater?

Accepted Answer

The impulse is the same in both cases.

Question 3

A 3.00-kg rifle fires a 0.00500-kg bullet at a speed of 300 m/s. Which force is greater in magnitude: the force that the rifle exerts on the bullet or the force that the bullet exerts on the rifle?

Accepted Answer

Both forces have the same magnitude.

Question 4

Car #1 is going 50 mi/h when it crashes into a stationary wall and comes to a halt. An identical car #2 is going 50 mi/h when it crashes head-on into, and sticks to, identical car #3 going 50 mi/h in the opposite direction. Which statement is correct?

Accepted Answer

Car #1 loses the same amount of momentum and the same kinetic energy in its collision as does car #2.

Question 5

Two objects with different masses collide and stick together. Compared to before the collision, the system of two objects after the collision has:

Accepted Answer

The same amount of total momentum but less total kinetic energy.

Question 6

Two objects with different masses collide and bounce off each other. Compared to before the collision, the system of two objects after the collision has:

Accepted Answer

The same amount of total momentum and the same total kinetic energy.

Question 7

Block A has mass $$1.00\ \mathrm{kg}$$ and block B has mass $$3.00\ \mathrm{kg}. $$The blocks collide and stick together on a level, frictionless surface. After the collision, the kinetic energy (KE) of block A is:

Accepted Answer

One-ninth the KE of block B.

Question 8

Block A ($$m_A = 1.00\ \mathrm{kg}) $$and block B ($$m_B = 3.00\ \mathrm{kg}) $$are forced together, compressing a spring. The system is released from rest on a level, frictionless surface. After release, how does $$p_A ($$the magnitude of momentum of block A) compare to $$p_B ($$the magnitude of momentum of block B)?

Accepted Answer

$$p_A = p_B$$

Question 9

Block A ($$m_A = 1.00\ \mathrm{kg}) $$and block B ($$m_B = 3.00\ \mathrm{kg}) $$are forced together, compressing a spring. The system is released from rest on a level, frictionless surface. After release, how does $$K_A ($$the kinetic energy of block A) compare to $$K_B ($$the kinetic energy of block B)?

Accepted Answer

$$K_A = 3K_B$$

Question 10

An open cart is rolling to the left on a horizontal surface. A package slides down a chute and lands in the cart. Which quantity or quantities have the same value just before and just after the package lands in the cart?

Accepted Answer

The horizontal component of total momentum.

Question 11

A yellow block and a red rod are joined together. Each object is of uniform density. The center of mass of the combined object is at the position shown by the black “X.” Which has the greater mass?

Accepted Answer

The red rod has the greater mass.

Question 12

Block A is initially moving to the right at $$6.00\ \mathrm{m/s}$$, while block B is initially at rest. The surface is level and frictionless. What is the velocity of the center of mass of the two blocks before the blocks collide? ($$m_A = 1.00\ \mathrm{kg}$$, $$m_B = 3.00\ \mathrm{kg})$$

Accepted Answer

$$1.50\ \mathrm{m/s}$$,\ to\ the\ right$

Question 13

Block A is initially moving to the right at $$6.00\ \mathrm{m/s}$$, while block B is initially at rest. The surface is level and frictionless. What is the velocity of the center of mass of the two blocks after the blocks collide? ($$m_A = 1.00\ \mathrm{kg}$$, $$m_B = 3.00\ \mathrm{kg})$$

Accepted Answer

$$1.50\ \mathrm{m/s}$$,\ to\ the\ right$

Question 14

Rank the following objects in order of the magnitude of the momentum, from largest to smallest: (A) Mass = 2.0 kg, kinetic energy = 2.0 J; (B) Mass = 1.0 kg, kinetic energy = 2.0 J; (C) Mass = 2.0 kg, kinetic energy = 4.0 J; (D) Mass = 4.0 kg, kinetic energy = 4.0 J.

Accepted Answer

D, C, A, B

Question 15

A soccer ball of mass $$0.45\ \mathrm{kg} is $$kicked from rest and reaches a speed of $$20\ \mathrm{m/s} in$$ $$0.10\ \mathrm{s}. $$What is the average force exerted on the ball?

Accepted Answer

$$90\ \mathrm{N}$$

Question 16

A $$2.0\ \mathrm{kg}$$ object moving at $$5.0\ \mathrm{m/s}$$ collides elastically with a $$3.0\ \mathrm{kg}$$ object at rest. What is the total momentum of the system after the collision?

Accepted Answer

$$10.0\ \mathrm{kg\cdot m/s}$$

Question 17

A $$0.150\ \mathrm{kg}$$ baseball moving at $$40.0\ \mathrm{m/s} is $$hit back at $$60.0\ \mathrm{m/s} by a $$bat. What is the magnitude of the change in momentum of the baseball?

Accepted Answer

$$15.0\ \mathrm{kg\cdot m/s}$$

Question 18

A $$1.0\ \mathrm{kg}$$ cart moving at $$2.0\ \mathrm{m/s}$$ collides and sticks to a $$2.0\ \mathrm{kg}$$ cart at rest. What is the final velocity of the combined carts?

Accepted Answer

$$0.67\ \mathrm{m/s}$$

Momentum, Impulse, and Collisions – Step-by-Step Physics Guidance

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