AP Physics 1 Work/Energy Review

A baguette is dropped off the top of the Eiffel Tower. What is true concerning of the mechanical energy of the ball as it falls?

• The potential energy of the baguette is conserved as it falls.

• The sum of the kinetic and potential energies of the baguette is a constant.

• The kinetic energy of the baguette is conserved as it falls.

• A) The total energy of the object increases as it falls since it gains speed.

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NGSS.HS-PS3-1

NGSS.HS-PS3-2

A spring is compressed by a force F against a wall as shown. Which of the following describes the sign of work done by the spring as it is being compressed?

• The spring does positive work since it is gaining potential energy.

• The spring does zero work since all the work is done by force F.

• The spring does negative work since it applies a force against the direction of its compressing motion.

• The spring works part-time at Chik Fil-A.

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NGSS.HS-PS3-1

NGSS.HS-PS3-2

In which of the following situations is kinetic energy decreasing?

• A lit tinsel llama is dropped from a building.

• A satellite is moving in a circular orbit around the moon.

• A baseball is headed upward after being thrown up in the air.

• An elevator is moving upward at a constant velocity.

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NGSS.HS-PS3-2

A roller coaster car of mass m has a speed of 0 m/s just before it starts to go down a hill as show above. Assume the roller coaster does not encounter any friction or air resistance. What is the speed of the roller coast car at point B?

• $\sqrt{gh}$

• $\sqrt{2gh}$

• $\sqrt{\frac{gh}{2}}$

• $\sqrt{\frac{2gh}{m}}$

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NGSS.HS-PS3-2

A dude drags a car mass M across a rough floor with a force of magnitude directed at an angle theta of above the horizontal as shown. If he drags the crate for a distance D, which of the following is equal to the work by the force of friction?

• $-F\cos\theta D$

• $-\mu mgD$

• $-\mu\left(mg-F\sin\theta\right)D$

• $-\mu\left(mg+F\cos\theta\right)D$

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NGSS.HS-PS2-1

Bill and Ted both push a crate of mass m crate across a floor with friction at constant speed. Bill pushes the crate d meters in 100 seconds. Ted takes 200 seconds to push the crate the same distance. Which of the following is true?

• More power is developed when Ted pushes the crate.

• More power is developed when Bill pushes the crate.

• An equal, non-zero amount of power is developed in both cases.

• Power is not developed in either case since the crate travels at constant velocity in both cases

A car of mass m is traveling at a speed of when the driver applies the brakes. The car moves a distance of d before it stops completely. What is the magnitude of the braking force required?

• $\frac{2d}{v^2}$

• $\frac{mv^2}{2d}$

• $\frac{2v^2}{d}$

• $\frac{mv}{d}$

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NGSS.HS-PS2-1

A beat is dropped from the edge of a cliff. Which of the following graphs best represents the beat's kinetic energy KE as a function of time t?

• 
• 
• 
• 

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NGSS.HS-PS2-1

NGSS.HS-PS3-2

A penguin of mass M is lifted upwards a vertical distance of H at a constant speed of v. Which of the following gives a correct expression for the power developed by the penguin as it is raised upward at constant speed?

• $Mgv$

• $\frac{mg}{v}$

• $\frac{mgh}{v}$

• $mgh$

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NGSS.HS-PS3-1

Jared holds a book still two feet above his desk. He then lowers the book at a constant speed and places it on the desk. Which of the following describes the change in total mechanical-energy of the book?

• The total mechanical energy is unchanged since there is no net work done as the book is lowered.

• The total mechanical energy decreases because Jared does positive work on the book.

• The total mechanical energy is unchanged because no work is done on the book while it is lowered.

• The total mechanical energy decreases, because Jared does negative work on the book.

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NGSS.HS-PS3-1