Question 1

A person lifts a box of mass 10 kg vertically upward by 2 meters at constant speed. What is the work done by the person on the box? (Take $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$196\ \mathrm{J}$$

Question 2

A crate is pushed across a rough floor with a constant force of $$50\ \mathrm{N}$$ over a distance of $$4\ \mathrm{m}. $$The force is applied at an angle of $$30^\circ$$ above the horizontal. What is the work done by the applied force?

Accepted Answer

$$173\ \mathrm{J}$$

Question 3

Which of the following scenarios involves negative work being done?

Accepted Answer

A person lowers a box slowly to the ground.

Question 4

A spring with spring constant $$k = 200\ \mathrm{N/m} is $$compressed by $$0.1\ \mathrm{m}. $$What is the elastic potential energy stored in the spring?

Accepted Answer

$$1\ \mathrm{J}$$

Question 5

A $$2\ \mathrm{kg}$$ block slides down a frictionless incline of height $$5\ \mathrm{m}. $$What is its speed at the bottom? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$9.9\ \mathrm{m/s}$$

Question 6

A $$0.5\ \mathrm{kg}$$ ball is dropped from a height of $$10\ \mathrm{m}$$ and rebounds to a height of $$6\ \mathrm{m}. $$How much energy was lost due to non-conservative forces?

Accepted Answer

$$4.9\ \mathrm{J}$$

Question 7

A $$3\ \mathrm{kg}$$ block slides $$4\ \mathrm{m}$$ down a rough incline, losing $$10\ \mathrm{J} to $$friction. If it starts from rest at a height of $$2\ \mathrm{m}$$, what is its speed at the bottom? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$5.1\ \mathrm{m/s}$$

Question 8

A $$0.2\ \mathrm{kg}$$ ball moving at $$5\ \mathrm{m/s}$$ collides elastically with a stationary $$0.2\ \mathrm{kg}$$ ball. What is the velocity of the first ball after the collision?

Accepted Answer

$$-5\ \mathrm{m/s}$$

Question 9

A $$1\ \mathrm{kg}$$ cart moving at $$3\ \mathrm{m/s}$$ collides inelastically with a $$2\ \mathrm{kg}$$ cart at rest. What is their final velocity after sticking together?

Accepted Answer

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

Question 10

A $$0.1\ \mathrm{kg}$$ ball moving at $$10\ \mathrm{m/s}$$ bounces off a wall and rebounds at $$8\ \mathrm{m/s} in $$the opposite direction. What is the magnitude of the impulse delivered to the ball by the wall?

Accepted Answer

$$1.8\ \mathrm{kg\cdot m/s}$$

Question 11

A $$0.5\ \mathrm{kg}$$ object is attached to a spring ($$k = 100\ \mathrm{N/m}) $$and is compressed $$0.2\ \mathrm{m}$$ from equilibrium. If released from rest, what is its speed as it passes through equilibrium?

Accepted Answer

$$2.8\ \mathrm{m/s}$$

Question 12

A $$2\ \mathrm{kg}$$ block slides on a horizontal surface with an initial speed of $$6\ \mathrm{m/s}. If $$the coefficient of kinetic friction is $$0.2$$, how far will the block slide before coming to rest? (Use $$g = 9.8\ \mathrm{m/s^2$})$$

Accepted Answer

$$6.0\ \mathrm{m}$$

Question 13

A $$0.3\ \mathrm{kg}$$ puck slides on ice and collides elastically with a $$0.5\ \mathrm{kg}$$ stationary puck. If the $$0.3\ \mathrm{kg}$$ puck was moving at $$4\ \mathrm{m/s}$$ before the collision, what is its velocity after the collision?

Accepted Answer

$$1.0\ \mathrm{m/s}$$

Question 14

A $$0.4\ \mathrm{kg}$$ ball moving east at $$3\ \mathrm{m/s}$$ collides inelastically with a $$0.6\ \mathrm{kg}$$ ball moving west at $$2\ \mathrm{m/s}. $$What is the velocity of the combined mass after the collision?

Accepted Answer

$$-0.2\ \mathrm{m/s}$$\ (west)

Question 15

A $$5\ \mathrm{kg}$$ object is acted on by a force that varies with position as $$F(x) = 4x (in $$newtons, with $$x in $$meters). How much work is done by this force as the object moves from $$x = 0 to$$ $$x = 2\ \mathrm{m}$$?

Accepted Answer

$$16\ \mathrm{J}$$

Work, Energy, and Momentum: Exam 2 Study Guide

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