Question 1

A 0.0053 kg marble is rolling at 0.65 m/s. What is its linear momentum?

Accepted Answer

$$p = 0.00345\ \mathrm{kg\cdot m/s}$$

Question 2

Which of the following best describes the direction of linear momentum for an object?

Accepted Answer

It is in the same direction as the velocity.

Question 3

A baseball (mass $$0.14\ \mathrm{kg}) $$approaches a bat at $$-38\ \mathrm{m/s}$$ and leaves at $$+58\ \mathrm{m/s}. $$What is the impulse delivered to the ball?

Accepted Answer

$$i = 13.4\ \mathrm{kg\cdot m/s}$$

Question 4

If a constant force $$F$$ acts on two boxes of different masses for the same time interval on a frictionless surface, which box will have the greater momentum after the force acts?

Accepted Answer

Both boxes will have the same momentum

Question 5

In the previous scenario, which box will have the greater velocity after the force acts?

Accepted Answer

The lighter box

Question 6

Which equation correctly expresses Newton's Second Law in terms of momentum for a system with changing mass?

Accepted Answer

$$\sum \vec{F} = \frac{\Delta \vec{p}}{\Delta t}$$

Question 7

A rifle of mass $$3.0\ \mathrm{kg}$$ fires a $$5.0\ \mathrm{g}$$ bullet at $$1200\ \mathrm{m/s}. $$What is the recoil speed of the rifle?

Accepted Answer

$$-2.0\ \mathrm{m/s}$$

Question 8

A small car and a large truck collide head-on and stick together. Which one experiences the greater change in momentum?

Accepted Answer

Both experience the same magnitude of momentum change

Question 9

Amy (150 lbs) and Gwen (50 lbs) push off each other on ice. If Amy slides at $$6\ \mathrm{m/s}$$, what is Gwen's speed?

Accepted Answer

$$18\ \mathrm{m/s}$$

Question 10

Which of the following statements about internal and external forces in a system is correct?

Accepted Answer

Internal forces always sum to zero and do not affect the net momentum.

Question 11

In a completely inelastic collision, which of the following is true?

Accepted Answer

Momentum is conserved, but kinetic energy is not.

Question 12

Two train cars of masses $$m_1$$ and $$m_2$$ collide and stick together. If $$m_1$$ moves at $$v_1$$ and $$m_2 at$$ $$v_2$$, what is their final velocity?

Accepted Answer

$$v_f = \frac{m_1$ v_1$ + m_2$ v_2$}{m_1$ + m_2$}$$

Question 13

A 1180 kg car traveling at $$+24\ \mathrm{m/s}$$ collides and attaches to a 2470 kg truck traveling at $$-16\ \mathrm{m/s}. $$What is the velocity of the combined vehicles after the collision?

Accepted Answer

$$v = -2.0\ \mathrm{m/s}$$

Question 14

Which of the following is true for an elastic collision in one dimension?

Accepted Answer

Both momentum and kinetic energy are conserved.

Question 15

In a one-dimensional elastic collision between two masses $$m_1$$ and $$m_2$$, with $$m_2$$ initially at rest, what is the final velocity of $$m_1$$?

Accepted Answer

$$v_{1f} = \frac{m_1$ - m_2$}{m_1$ + m_2$} v_{10}$$

Question 16

Which statement about the center of mass of a system is correct?

Accepted Answer

It is the point where the system can be balanced in a uniform gravitational field.

Question 17

For two masses $$m_1$$ and $$m_2 at $$positions $$x_1$$ and $$x_2$$, what is the formula for the center of mass position $$x_{cm}$$?

Accepted Answer

$$x_{cm} = \frac{m_1$ x_1$ + m_2$ x_2$}{m_1$ + m_2$}$$

Question 18

Where is the center of mass of a baseball bat located?

Accepted Answer

Closer to the thick end

Question 19

The total mass $$M of a $$system multiplied by the acceleration of its center of mass $$A_{cm} is $$equal to:

Accepted Answer

$$M A_{cm} = \sum F_{net,ext}$$

Linear Momentum and Collisions: Study Notes (Chapter 9)

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