Question 1

A baseball bat strikes a ball, exerting a force over a short time interval. If the force-time graph for the collision is a triangle with a base of $$0.02 s $$and a peak force of $$800 N$$, what is the impulse delivered to the ball?

Accepted Answer

$$16 kg$$\cdot m/s$

Question 2

Which of the following best describes the impulse-momentum theorem?

Accepted Answer

$$J = F_{avg} \Delta t = m(v_f - v_i)$$

Question 3

A clay ball and a superball of equal mass are dropped from the same height onto a hard surface. The superball bounces back while the clay sticks. Which receives a greater impulse from the surface?

Accepted Answer

The superball, because its change in momentum is greater.

Question 4

A rifle fires a bullet. If the mass of the rifle is $$4 kg $$and the mass of the bullet is $$0.02 kg$$, and the bullet leaves the barrel at $$500 m/s$$, what is the recoil velocity of the rifle?

Accepted Answer

$$-0.5 m/s$$

Question 5

Which statement about momentum in a closed system is correct?

Accepted Answer

Total momentum is conserved if no external forces act.

Question 6

Two ice skaters, Skater A (mass $$60 kg) $$and Skater B (mass $$80 kg$$), push off from each other and move in opposite directions. If Skater A moves at $$3 m/s$$, what is Skater B's velocity?

Accepted Answer

$$-2.25 m/s$$

Question 7

A $$0.15 kg $$baseball moving at $$40 m/s is $$hit by a bat and reverses direction, leaving at $$60 m/s. $$What is the impulse delivered by the bat?

Accepted Answer

$$15 kg$$\cdot m/s$

Question 8

Which of the following is true for an inelastic collision?

Accepted Answer

Kinetic energy is not conserved, but momentum is.

Question 9

A $$2 kg $$cart moving at $$5 m/s $$collides and sticks to a $$3 kg $$cart at rest. What is their final velocity after the collision?

Accepted Answer

$$2 m/s$$

Question 10

Which formula correctly expresses the conservation of momentum for a two-object system before and after a collision?

Accepted Answer

$$m_1 v$$_{1i} + $$m_2 v$$_{2i} = $$m_1 v$$_{1f} + $$m_2 v$$_{2f}$$

Question 11

A $$0.5 kg $$ball moving at $$10 m/s $$collides elastically with a stationary $$0.5 kg $$ball. What are their velocities after the collision?

Accepted Answer

First ball: $$0 m/s$$, second ball: $$10 m/s$$

Question 12

A force of $$200 N $$acts on a $$0.1 kg $$object for $$0.05 s. $$What is the change in velocity of the object?

Accepted Answer

$$100 m/s$$

Question 13

Which scenario best illustrates the concept of impulse?

Accepted Answer

A tennis player hitting a ball with a racket over a short time interval.

Question 14

If two objects collide and stick together, what type of collision has occurred?

Accepted Answer

Perfectly inelastic

Question 15

A $$1 kg $$object moving at $$4 m/s $$collides with a $$2 kg $$object moving at $$-2 m/s. If $$they stick together, what is their final velocity?

Accepted Answer

$$0 m/s$$

Question 16

Which of the following is NOT a correct statement about impulse?

Accepted Answer

Impulse is always equal to the change in kinetic energy.

Question 17

A $$0.2 kg $$hockey puck is struck by a stick, causing its velocity to change from $$-3 m/s to$$ $$5 m/s. $$What is the impulse delivered to the puck?

Accepted Answer

$$1.6 kg$$\cdot m/s$

Question 18

During a car crash, airbags help reduce injuries by:

Accepted Answer

Increasing the time over which the force acts, reducing the force.

Question 19

Which of the following is a correct unit for impulse?

Accepted Answer

$$kg\cdot m/s$$

Question 20

A $$0.3 kg $$soccer ball is kicked, changing its velocity from $$0 to$$ $$20 m/s in$$ $$0.1 s. $$What average force was applied?

Accepted Answer

$$60 N$$

Impulse, Momentum, and Conservation of Momentum – Study Guide

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