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Lesson: Gravitational Potential Energy

Sample Question Videos

Worksheet • 11 Questions • 2 Videos

Q1:

An elevator car of mass 1 . 5 0 × 1 0 3 kg is pulled 40.0 m vertically upward at constant speed by its cable. An average friction force of 100 N resists the motion of the elevator car.

What work is done on the elevator car by the cable?

What work is done on the elevator car by the force of gravity?

What is the total work done on the elevator car?

Q2:

A cruise ship is docked in a harbour. The level of the dock is 2.15 m above the water line. A woman on the cruise ship stands on a deck 55.5 m above the water line. She pushes a 36.0-g-mass pebble off the deck. A man standing on the dock holds out a net 1.20 m above the top of the dock and catches the pebble in the net. Assume that vertically upward motion corresponds with positive displacement.

How much work is done by gravity on the pebble?

How much does the gravitational potential energy of the pebble change?

Taking gravitational potential energy at the water line to be zero, what is the gravitational potential energy of the pebble on the deck of the cruise ship?

Taking gravitational potential energy at the water line to be zero, what is the gravitational potential energy of the pebble when it is caught in the net?

Taking gravitational potential energy at the water line to be 21.5 J, what is the gravitational potential energy of the pebble on the deck of the cruise ship?

Taking gravitational potential energy at the water line to be 21.5 J, what is the gravitational potential energy of the pebble when it is caught in the net?

Q3:

Suppose a 350 g kookaburra (a large kingfisher bird) picks up a 75 g snake and raises it 2.5 m from the ground to a branch.

How much work did the bird do on the snake?

How much work did the bird do to raise its own center of mass to the branch?

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