3.1 Work & Power

Multiple Choice

What units do we use to measure work?

• watts
• newtons
• joules
• meters

Multiple Choice

Which of the following is true about work?

• It measures how quickly an object accelerates
• It measures how much effort is applied over a distance.
• It measures the change of an object's rate of speed.
• It measures how much time it takes to move an object.

Multiple Choice

The formula for work is

• work/time (P = W/t)

• force × distance (W = Fd)

• distance/time (s = d/t)

• mass × acceleration (F = ma)

Multiple Choice

In which case is work being done?

• A

• B

• C

• D

Multiple Choice

Joel and Jerry push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do on the car.

• Joel does 75% more work than Jerry.

• Joel does 50% more work than Jerry.

• Jerry does 50% more work than Joel.

• Joel does 25% more work than Jerry.

• Neither of them does any work.

Multiple Choice

A student needs 10 Newtons of force to lift a box to the top of a 2 meter shelf. How much work do they do?

• 12 J

• 8 J

• 20 J

• 5 J

Multiple Choice

A worker climbs a ladder and does 8 J of work on a 2 N object. What is the distance they lift the object?

• 18 m

• 4 m

• 10 m

• 6 m

Multiple Choice

Which of these are measurements of power?

• 100 joules
• 100 watts
• 100 second

• 100 hertz

Multiple Choice

Two workers use 100 N of force to move a sofa 2 meters in 2 seconds. How much power is required?

• 100 watts

• 400 watts

• 104 watts

• 50 watts

Multiple Choice

How much power is used when 9000 J of work are done in 0.5 seconds?

• 4,500 W

• 18000 W

• 9453 W

• 917.4 W