Power

GCSE Physics

It is said that power corrupts, but actually it's more true that power attracts the

corruptible. The sane are usually attracted by other things than power

Some things that are powerful…

Who’d man!!??

World’s Strongest Man CompetitionAtlas Stones

Work done = Force x distance

Energy = (160 x 10) x 2

= 3,200 J

Compared to climbing the stairs?

Learning Intentions

By the end of the lesson we will be able to…

- Define the term ‘power’ using it correctly in the context of physics

- Recall the equation for power, including the units

- Calculate power in a number of simple experiments

Page 10The quantity of energy transferred or work

done is more useful when we consider how quickly it can happen.

Power is the rate of doing workA construction crane is regarded as

powerful if it can lift a heavy steel beam in a short time

Power

Calculating Power

The equation for power-

Power =Work Done

Time Taken

W tP = /

Joule secondWatt = /

Word Equation

Dimensions

Units

Example

A fork lift truck can raise a load of 315 kg to a height of 2 m in 20 seconds. What is the power developed?

Work Done = F x d

= (315 x 10) x 2 = 6300 JPower = Energy / Time Taken

= 6300 / 20

= 315 W

You try this one…

A mouse of mass 30 g runs up a 2 m curtain in 4 seconds. Calculate its power in Watts

Work Done = (0.03 x 10) x 2

= 0.6 JPower = Work Done / Time taken

= 0.6 / 4

= 0.15 W