AP Physics Work

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 baguette and the Earth are a system

• 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.

Tags

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.

Tags

NGSS.HS-PS2-1

NGSS.HS-PS3-1

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-PS3-1

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?

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?

Tags

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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Tags

NGSS.HS-PS2-1

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.

A stick figure of mass 50kg running at speed v grabs a light rope that hangs from a ceiling of height h and swings to a maximum height of h, In another room with a ceiling of height h/2, a second stick figure with mass 100 kg running at the same speed v grabs a light rope hanging from the ceiling and swings to a height of h. How does the maximum height reached by the two stick figures compare and why?

• The first stick figure swings to a higher height since he swings from a higher rope.

• The second stick figure swings to a higher height since he has more mass.

• The two stick figures reach the same height, because the length of the second rope offsets the mass of the second stick figure.

• Both stick figures swing to the same height because they have the same initial speed and mass cancels out

Tags

NGSS.HS-PS2-1

NGSS.HS-PS3-1

NGSS.HS-PS3-2

The graph on the right shows the kinetic energy over time for a lit tinsel llama in motion. At time t = 0, the potential energy of the llama is 10 J. Determine the potential energy of the object at time t = 9 s.

• 4 J

• 10 J

• 8 J

• 2 J

Tags

NGSS.MS-PS3-1

An object initially at rest falls from a height H until it reaches the ground. Two of the following energy bar charts represent the kinetic energy K and gravitational potential energy Ug of the object-Earth system at two positions. The first position is when the object is initially released, and the second position is when the object is halfway between its release point and the ground. Which chart could represent the mechanical energy of the object-Earth system?

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