# Work, Energy and Power

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Work is done whenever energy is transferred. What is 'work'? and what is is measured in?
the amount of energy transferred from one form to another when a force causes a movement of some sort (energy changed not total). In Joules (J)
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Formula for work?
W = Fx ( F is the force causing motion and is fixed - this assumes the direction of the force is the same as the movement) ( x is distance moved )
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one joule is...
the work done when a force of one newton moves an object one meter
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When the force isnt in the same direction as the movement?
COnsider vertical and horizontal components. W = F(cos)
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Power is the rate of doing work. Give another definition and the equation.
The amount of energy transformed from one form to another per secong. Power (P) = Work done (W) / Time (T)
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Watts are the unit of power. What are they defined as?
the rate of energy transfer equal to 1 joule per second (Js^-1)
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Different power equation?
Power = Force x Velocity. (Or if force and motion are in different directions, P = Fv(cos theta)
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Formula for kinetic energy
Ek = 1/2 mv^2 and Ek = Fx (work done)
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What is Gravitational potential energy and what is its formula? (it is equal to the work done in moving the object)
The energy an object has due to its position in a gravitational field. Ep = mgh (Ep = W = Fxh)
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State the principle of conservation of energy
Energy can't be created or destroyed. Energy can be transferred from one form to another but the total amount of energy in a closed system will not change. Total energy in = Total energy out
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All energy transfers involve losses. These arent useful and you cant get them back. Examples?
Heat, Sound
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What is efficiency?
a measure of how well a device converts the energy you put in into the enrgy you want to give out. = ((useful output energy) / (total input energy)) x 100
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## Other cards in this set

### Card 2

#### Front

Formula for work?

#### Back

W = Fx ( F is the force causing motion and is fixed - this assumes the direction of the force is the same as the movement) ( x is distance moved )

one joule is...

### Card 4

#### Front

When the force isnt in the same direction as the movement?

### Card 5

#### Front

Power is the rate of doing work. Give another definition and the equation.