AP Physics Energy

How are work and energy related? 

• The work done by an external force acting on an object causes a change in the mechanical energy of the object.

• Work is the same thing as energy.  They are equal. 

• Energy is m*g*h, and work is 1/2*m*v²

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NGSS.MS-PS3-4

Use the law of conservation of energy (assume no friction) to find "E" for a 500-kg roller coaster following this path.

• 51.0 m/s

• 40.8 m/s

• 28.3 m/s

• 31.6 m/s

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A crane lifts a steel beam weighing 8,000N, 300m in the air, then drops it onto a 20m high building below (for science!). The steel beam breaks through the ceiling. Assume that air resistance is negligible. Select the statement that best describes the scenario above.

• The beam has less energy when landing on the ground than it started with due to losing some to its surroundings

• The beam has the same amount of energy as it began with

• The kinetic energy as the beam touches the ground is equal to the potential energy it began with.

• The beam has a velocity of 19.8 m/s as it reaches the ground

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NGSS.MS-PS3-1

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NGSS.MS-PS3-5

Rank the scenarios from least to greatest kinetic energy right before they hit the ground

• 2<3<1<4

• 2<1<3=4

• 2<1<3<4

• 1=2=3=4

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NGSS.MS-PS3-1

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Which law states that the total energy in a closed system remains constant?

• Law of Conservation of Momentum

• Law of Conservation of Energy

• Newton's First Law of Motion

• Hooke's Law

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NGSS.MS-PS3-4

NGSS.MS-PS3-5

In which of the following situations do your arms do work on books?

• holding a heavy stack of books while standing

• carrying a heavy stack of books

• dropping a stack of books onto a table

• picking up a pile of books from the floor

How much work is done in holding a 15 N sack of potatoes while waiting in line at the grocery store for 3 minutes?

• 15 J

• 45 J

• 0 J

• 5 J

Mr. B's and Mr. P's classes competed in a game of tug of war. Mr. B's class pulled to the right with a force of 4,000 N. Mr. P's class pulled to the left with a force of 5,000 N. As a result the rope moved 5.1 m to the left. How much work was done by the net force?

• 4100 J

• 3100 J

• 5100 J

• 45900 J

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NGSS.MS-PS2-2

How much work is done carrying a 10-N box horizontally across a floor for 8 m?

• 80 J

• 10 J

• 8 J

• 0 J

You do work against gravity when you walk up some stairs.

• True

• False

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