AP Physics Work

Which is an example of work being done?

• plants growing

• people sitting down

• car towing a boat down the road

• turning a light on

Tags

NGSS.MS-PS3-5

Which are correct units for power?

• N x s

• N x m

• J

• J/s

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 mgh, and work is mv²/2

Tags

NGSS.HS-PS2-1

If you pull the trolley along a flat floor horizontally. Which force do you use to calculate the work done.

• Weight

• Pulling force

• Normal forrce

• Friction

Tags

NGSS.HS-PS2-1

If the net work done on an object is negative, then the object’s kinetic energy...

• decreases

• remains the same

• increases

• is zero

Tags

NGSS.HS-PS3-1

On a force versus change in position graph, the area under the curve is a representation of...

• power

• KE

• PE

• work

A net force (Fcosθ) acts on an object moving in the

positive x-direction along the axis over a distance of 4

meters, depicted in the graph at right. Find the work done by the force in the interval from 0.0 to 2.0 m.

• 0 J

• 3 J

• 3/cosθ J

• 6 J

Tags

NGSS.HS-PS2-1

A child pushes horizontally on a box of mass m which moves with constant speed v across a horizontal floor.<\/p>

The coefficient of friction between the box and the floor is μ. At what rate does the child do work on the box?<\/p>

• μmgv<\/p>

• mgv<\/p>

• μmg/v<\/p>

• mgv/μ<\/p>

A man stands in an elevator as it begins to ascend. Does the normal force from the floor do work on the man?

• Yes, and the work done will be positive.

• Yes, and the work done will be negative.

• Yes, but the sign can’t be determined.

• No.

Tags

NGSS.HS-PS2-1

A 1-kg object is released from rest at the top of a rough-surfaced incline. The object slides without rotating to the bottom of the incline. The object’s kinetic energy at the bottom must be...

• equal to the block’s gravitational potential energy when it was released, because total mechanical energy must be conserved.

• equal to the block’s gravitational potential energy when it was released, because the gain in kinetic energy compensates for the mechanical energy lost to thermal energy on the rough incline.

• less than the block’s gravitational potential energy when it was released, because the gravitational potential energy was converted both to thermal energy and to kinetic energy.

• less than the block’s gravitational potential energy when it was released, because the work done by the friction force must be greater than the block’s gain in kinetic energy.

Tags

NGSS.HS-PS3-4