Unit 3 Assessment Review: Work & Energy

What is the Law of Conservation of Mechanical Energy?

• Energy cannot be created or destroyed.

• The total energy of an isolated system remains constant.

• Work done is equal to the change in kinetic energy.

• All of the above.

If an object is in freefall, what happens to its kinetic energy as it falls?

• The kinetic energy increases.

• The kinetic energy decreases.

• The kinetic energy remains constant.

• The kinetic energy becomes zero.

A 5 kg mass is dropped from a height of 21 m. What is its potential energy as it hits the ground?

• 0 J

• 105 J

• 1030 J

• 1102 J

For the roller coaster ride shown below, at which point is the value of potential energy the greatest?

• A

• B

• C

• D

• E

At a roller coaster ride, a single roller coaster car with two passengers (total mass of 735 kg) drops from a height of 100 m. Find its velocity as it reaches the bottom of the track.

• 85 m/s

• 120 m/s

• 3605 m/s

• 7210 m/s

If a machine does 600 J of work in 6 seconds, what is its power?

• 6 W

• 10 W

• 60 W

• 100 W

What is the power output if a force of 60 N is applied to move an object 10 meters in 20 seconds?

• 1.2 W

• 30 W

• 120 W

• 3000 W

In a wheel and axle system, if the radius of the wheel is 8 inches and the radius of the axle is 2 inches, what is the mechanical advantage?

• 0.5

• 1

• 2

• 4

What is the mechanical advantage of a lever with a load arm of 10 meters and an effort arm of 2 meters?

• 0.25

• 2

• 4

• 5

How does the length of an inclined plane affect its mechanical advantage?

• It has no effect.

• Longer length increases mechanical advantage.

• Longer length decreases mechanical advantage.

• It depends on the angle of the incline.