Power & Work Done

This lesson covers:

1What 'power' is and how to calculate it

Power is the at which energy is transferred, or the rate at which is done.

rate
work

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The terms 'Work' or 'work done' refer to the energy transfer that occurs when a force is used to m an object by a certain d

ove
istance

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2

The formula for power is:

(You may select more than one)

P = WtP\ =\ \frac{W}{t}

P = WtP\ =\ Wt

P = EtP\ =\ Et

P = EtP\ =\ \frac{E}{t}

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2

Three lightning bolts representing power units.

What are the units of power? 

Volts (V)

Coulombs (C)

Watts (W)

Amps (A)

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A toaster consumes 40,500 J in 45 s, what is its power consumption?

900

W

W

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A 25 W light bulb was turned on and consumed 650 J of energy before it was turned off. How long was the light bulb on for?

26

s

s

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A wind turbine generates 150 MJ of energy in one minute. What is the rate of power generation?

2500000

W

W

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A phone battery can hold 18,000 joules of energy, and the phone charger has a power rating of 2 W.


How many hours will it take to charge the phone from completely flat to full battery?

2.5

hours

hours

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