Key Concepts When is work done on an object? How do you determine the work done on

an object? What is power?

Key Terms Work Joule power

Ideas

Scientific Meaning of Work - When a force moves an object.

Work = Force X Distance W=F x D

The distance the object moves must be in the same direction as the force applied.

Force is measured in newtons Distance is measured in meters Work is measured in newton-meter or joules

Ex. an apple weighs about 1 newton. If you move it 1 meter you have done 1 joule of work

If you lifted an object weighing 200N through a distance of .5m, how much work would you do?

A 600 N woman lifts a 100 N suitcase a distance of .5 meters. How much work did she do on the suitcase?

Ideas

Power - the rate at which work is being done,

or the amount of work per unit of time.

Power = Work = Joule = watt (W) Time sec

Power = Force X Distance = watt (W) Time

1000 watts = kilowatt - used to measure large amounts of power

A motor exerts a force of 12,000N to lift an elevator 8.0m in 6.0 s. What is the power of the motor?

A crane lifts an 8.000 N beam 75m to the top of a building in 30 s. What is the crane’s power?