Q: Which of the following best describes the work done by a force $$F$$ acting at an angle $$\theta to $$the direction of displacement $$d$$?

$$W = F \times d \times \cos\theta$$

Question 1

A 15 kg suitcase is lifted vertically 3.0 m onto a platform at constant speed. How much work is done on the suitcase by the lifting force? (Assume $$g = 9.8 \ \mathrm{m/s^2$})$$

Accepted Answer

$$147 \ \mathrm{J}$$

Question 2

Which of the following best describes the work done by a force $$F$$ acting at an angle $$	heta to $$the direction of displacement $$d$$?

Accepted Answer

$$W = F 	imes d 	imes \cos	heta$$

Question 3

A vacuum cleaner is pulled 3.0 m by a force of 50.0 N at an angle of $$30.0^\circ$$ above the horizontal. How much work is done by the force?

Accepted Answer

$$130 \ \mathrm{J}$$

Question 4

Which of the following is the correct formula for kinetic energy?

Accepted Answer

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

Question 5

A 7.0 kg bowling ball moves at 2.0 m/s. What is its kinetic energy?

Accepted Answer

$$28 \ \mathrm{J}$$

Question 6

A 2.45 g ping-pong ball must have the same kinetic energy as a 7.0 kg bowling ball moving at 2.0 m/s. What speed must the ping-pong ball have?

Accepted Answer

$$1510 \ \mathrm{m/s}$$

Question 7

Which of the following statements best describes the Law of Conservation of Energy?

Accepted Answer

Energy is never created or destroyed, only transferred or transformed.

Question 8

A 10.0 kg sled is kicked on a frozen pond, giving it an initial speed of 2.0 m/s. If the coefficient of friction between the sled and the ice is 0.10, how far does the sled move before stopping? (Assume $$g = 9.8 \ \mathrm{m/s^2$})$$

Accepted Answer

$$4.1 \ \mathrm{m}$$

Question 9

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

Accepted Answer

$$PE = mgh$$

Question 10

A 2.0 kg ball is resting on a hill that is 5.0 m high. What is its gravitational potential energy relative to the base of the hill? (Assume $$g = 9.8 \ \mathrm{m/s^2$})$$

Accepted Answer

$$98 \ \mathrm{J}$$

Question 11

A stuntman of mass 80 kg is attached to a bungee cord with an unstretched length of 15.0 m. He jumps from a bridge 50.0 m above a river. When he stops, the cord is stretched to 44.0 m. If the spring constant of the bungee is $$18.8 \ \mathrm{N/m}$$, what is the total potential energy stored in the cord at maximum stretch?

Accepted Answer

$$8,000 \ \mathrm{J}$$

Question 12

A child of mass 30 kg starts from rest and slides down a frictionless slide from an initial height of 5.0 m. What is her speed at the bottom of the slide? (Assume $$g = 9.8 \ \mathrm{m/s^2$})$$

Accepted Answer

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

Question 13

Which of the following is the correct formula for elastic potential energy stored in a spring?

Accepted Answer

$$PE = \frac{1}{2}kx^2$

Question 14

Which of the following best describes mechanical energy?

Accepted Answer

The sum of kinetic and potential energy in a system.

Question 15

A curtain needs to be raised at a constant speed in as short a time as possible. The available motors are rated at 1.0 kW, 2.5 kW, 3.0 kW, and 5.5 kW. Which motor is best suited for the job?

Accepted Answer

5.5 kW

Question 16

Which of the following is the correct definition of power in physics?

Accepted Answer

The rate at which work is done or energy is transferred.

Question 17

Which equation represents the Work-Kinetic Energy Theorem?

Accepted Answer

$$W_{net} = \Delta KE$$

Question 18

A 60 W light bulb is left on for 2 hours. How much energy does it consume in joules?

Accepted Answer

$$432,000 \ \mathrm{J}$$

Question 19

A person pushes a box with a force of 100 N at an angle of $$60^\circ to $$the horizontal for a distance of 5 m. How much work is done by the force?

Accepted Answer

$$250 \ \mathrm{J}$$

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