Work and Energy

What is the S.I unit of work?

• N.m²

• (Kg.m²) / s²

• J/m

• J

Tags

NGSS.MS-PS3-5

In which scenario is work = 0 J ?

• Pushing a stationary wall

• Pulling a trolley car

• Pushing a book across the table

• Dropping a set of keys from a height, h.

Power depends on force and speed.

• True

• False

The coefficient of kinetic friction between a large box and the floor is 0.21. A person pushes horizontally on the box with a force of 165 N for a distance of 2.8 m. If the mass of the box is 72 kg, what is the total work done on the box? (Round your answer to a whole number)

• 51

• 49

• 47

• 45

Tags

NGSS.HS-PS3-1

Work is zero if the force has a component in the direction opposite of motion.

• True

• False

A 3 kg plate is tossed across the room with an acceleration of 13 m/s² in 2.5 sec. Calculate the amount of power it took to toss the plate.

• 290.5 W

• 1267.5 W

• 507 W

• 3000 W

Tags

NGSS.HS-PS2-1

An object weighing 20 N moves horizontally toward the right a distance of 5.0 m. What is the work done on the object by the force of gravity?

• The work done on the object by the force of gravity is 50 J.

• The work done on the object by the force of gravity is zero joules.

• The work done on the object by the force of gravity is 4.0 J.

• The work done on the object by the force of gravity is 0.25 J.

• The work done on the object by the force of gravity is 100 J.

You pick up a 3.8 kg can of paint from the ground and lift it to a height of 1.4 m. You hold the can stationary for half a minute, waiting for a friend on a ladder to take it. How much work do you do during this time (when the can of paint was stationary)?

• 52 J

• 30 J

• 0 J

• 25 J

If the net work done on an object is positive, what can you conclude about the object's motion?

• The object is speeding up.

• The object is moving with a constant velocity.

• The object is slowing down.

• The object is at rest; its position is constant.

Tags

NGSS.HS-PS2-1

You raise a bucket of water from the bottom of a well that is 12 m deep. The mass of the bucket and the water is 5.00 kg, and it takes 15 s to raise the bucket to the top of the well. How much power is required?

• 39 W

• 41 W

• 43 W

• 45 W

Tags

NGSS.HS-PS3-1