Work, Power, and Efficiency

Work is a measure of the energy needed to apply a force across a _______.

• time
• distance
• gravity
• object

Efficiency is a ______ of what you put in versus what you get out of a system.

• source
• ratio
• multiplication
• addition

An object has a weight of 200 N and is moved 3 meters.  How much work is done?

• 66.7 J
• 600 J
• 203 J
• 0.015 J

Tags

NGSS.HS-PS3-2

A light bulb consumes 100 Watts. If it is left on for 20 seconds, how much work does it do?

• 5 J

• 2,000 J

• 0.2 J

• 100 J

Tags

NGSS.HS-PS3-1

For there to be work, there must always be distance.

• True
• False

Power does not depend on...

• strength
• work
• time
• any of these

How much work is done in holding a 15 N sack of potatoes while waiting in line at the grocery store for 3 minutes?

• 15 J
• 45 J
• 0 J
• 5 J

What is the difference between calculating power and work?

• Power takes into account the time it takes to complete a task
• Work takes into account the time it takes to complete a task
• Power is force/area
• Work is force/area

You are pushing a car as hard as you can for 5 minutes, but cannot get it to move.  How much work have you done on the car?

• There is not enough information to calculate the work.
• If you used 20 newtons of force, you will have done 100 Joules of work
• None. There was no movement.
• None of the answers are correct.

Find the work of a turtle that has a force of 27 newtons and travels a distance of 3 meters.

• 81 watts
• 81 joules
• 9 watts
• 9 joules