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What is the Difference between Power and Energy?

The equation that connects power and energy is

Power = Energy ÷ Time.

This equation is important!

Power
is the rate at which energy
is transferred.

Power
is measured in Watts. 1 Watt = 1 Joule per
second.

What is the Power Output of a Motor?

Q. A motor lifts a
15 kg mass by 3
metres in 8 seconds.

What is the motor's power output
?

A. The motor has transferred rotational energy

into gravitational
potential energy.

GPE = mass x gravity x height.

= 15
x 10 x 3

= 450
J.

When the 15 kg mass
is 3
metres high it has

gained 450 J of gravitational
potential energy.

It has gained this energy in 8 seconds.

Power = Energy ÷ Time

= 450
÷ 8

=
56·25 W.

The motor's power output is 56·25 Watts.

There is also an equation for power in electricity.

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