Question 1

A 1 kg cart moving at 4 m/s collides head-on with a 2 kg cart moving at 2 m/s in the opposite direction on a frictionless track. If the collision is perfectly inelastic, what is the final velocity of the combined mass after the collision?

Accepted Answer

$$0.67\ \mathrm{m/s}$$\ to\ the\ right$

Question 2

Which of the following best describes the law of conservation of linear momentum for a system of particles?

Accepted Answer

The total momentum of the system remains constant if the net external force is zero.

Question 3

A ball of mass $$m$$ with initial velocity $$v_0$$ collides elastically with a stationary ball of mass $$2m. $$What are the final velocities of the two balls?

Accepted Answer

$$v_1$$ = -\frac{1}{3}$$v_0$$,\ $$v_2$$ = \frac{2}{3}$$v_0$$

Question 4

Which of the following equations correctly expresses the conservation of momentum for a perfectly inelastic collision between two objects of masses $$m_1$$ and $$m_2$$?

Accepted Answer

$$m_1$$\vec{v}_{1i} + $$m_2$$\vec{v}_{2i} = ($$m_1$$ + $$m_2$$)\vec{v}_f$$

Question 5

A 2.0 kg object moving at 3.0 m/s strikes a 1.0 kg object at rest. After the collision, the 2.0 kg object moves at 1.5 m/s at $$30^\circ$$ from its original direction. What is the $$y-$$component of the velocity of the 1.0 kg object just after the collision?

Accepted Answer

$$-2.4\ \mathrm{m/s}$$

Question 6

Which of the following is the correct expression for the kinetic energy of an object of mass $$m$$ moving at velocity $$v$$?

Accepted Answer

$$K = \frac{1}{2}mv^2$

Question 7

A spring with spring constant $$k is $$compressed by a distance $$x. $$What is the elastic potential energy stored in the spring?

Accepted Answer

$$U_{el} = \frac{1}{2}kx^2$

Question 8

In a Newton’s Cradle, if two balls are released from one end, what happens to the balls on the opposite end?

Accepted Answer

Two balls move out with the same speed as the released balls.

Question 9

A 1 kg block and a 3 kg block are initially at rest, compressed against a spring. When released, the 3 kg block moves to the right at 2 m/s. What is the velocity of the 1 kg block?

Accepted Answer

$$6\ \mathrm{m/s}$$\ to\ the\ left$

Question 10

Which of the following is the correct unit for linear momentum in the MKS system?

Accepted Answer

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

Question 11

A car of mass $$m$$ traveling at velocity $$v$$ collides with a stationary truck of mass $$3m$$ and they stick together. What is their final velocity?

Accepted Answer

$$\frac{v}{4}$$

Question 12

Which of the following statements is true for an isolated system undergoing a collision?

Accepted Answer

Total momentum is always conserved.

Question 13

A billiard ball of mass $$m$$ moving at $$4\ \mathrm{m/s}$$ collides elastically with an identical stationary ball. After the collision, the first ball moves at $$2\ \mathrm{m/s} at$$ $$45^\circ to $$its original direction. What is the speed of the second ball after the collision?

Accepted Answer

$$2\ \mathrm{m/s}$$

Question 14

Which of the following best describes a perfectly inelastic collision?

Accepted Answer

The objects stick together and move with a common velocity after the collision.

Question 15

Which of the following is the correct formula for gravitational potential energy?

Accepted Answer

$$U_g = mgh$$

Question 16

A system is isolated and two objects collide. Which of the following must be true?

Accepted Answer

The total momentum before and after the collision is the same.

Question 17

Which of the following is the correct expression for the work done by a constant force $$\vec{F}$$ over a displacement $$\vec{d}$$?

Accepted Answer

$$W = \vec{F} \cdot \vec{d}$$

Question 18

A block slides across a rough surface and comes to rest due to friction. Which form of energy increases as a result?

Accepted Answer

Thermal energy

Question 19

In a two-dimensional collision, which components of momentum are conserved?

Accepted Answer

Both $$x$$ and $$y$$ components

Conservation of Momentum and Collisions: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards