POWERPower –

Power =

P = ___ = ___

Units = ( ) = ____ = ___

Sample Problem:A crane lifts an 8000 N beam 75 m to the

top of a building in 30 s. How much power does the crane use?

More Power Units

Kilowatt (kw) =

Megawatt (mw)

Kilowatts =

Horsepower =

1 horsepower =

POWERPower –

Power = = =

Units = ( ) = =

Sample Problem:A crane lifts an 8000 N beam 75 m to the

top of a building in 30 s. How much power does the crane use?

the rate at which work is done

The rate at which energy is transferred from one object to another.

work done time interval

W Fd t t

Watt W Nm s

Js

P = W = Fd t t

Force = Distance =

Sample Problem:A crane lifts an 8000 N beam 75 m to the top of a

building in 30 s. How much power does the crane use?

8000 N 75 m Time = 30 s

P = 8000 N x 75 m 30 s

600,000 J 30s

=

20,000 W or 20 kW P =

More Power Units

Kilowatt (kw) =

Megawatt (mw)

Kilowatts =

Horsepower =

1 horsepower =

1000 watts

1 million watts

electricity (household electric bill)

engines (cars are rated in)

.75 kilowatt