# Energy Transfers and Efficiency - Physics

• Created by: becky.65
• Created on: 30-12-15 11:30
List 8 different forms of energy
Light, sound, kinetic, electrical, gravitational potential, elastic potential, chemical and nuclear
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What does the principle of conservation of energy state?
That energy cannot be created or destroyed, it is only possible to change it from one form to another, or transfer it from one place to another
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Does the total amount of energy ever change?
No it always stays the same
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What two types of energy we get out of a machine consist of?
Useful energy and wasted enegry
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What is useful energy?
Energy which is transferred to the place we want and in the form we want it in
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What is wasted energy?
Energy which is not usefully transferred
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What eventually happens to both useful and wasted energy?
They will eventually be transferred to the surroundings and make them warm up
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Why is energy often wasted in a machine?
Because of friction between moving parts
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What is the energy supplied to a machine often called?
Input energy
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What is the input energy equal to?
input energy = useful energy delivered + wasted energy
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What are some ways we can reduce energy transfers out of homes?
Loft insulation, cavity wall insulation, double glazing, draught proofing and aluminium foil behind radiators
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What does the U-value of a material tells us?
How much energy per second passes through it
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What does a lower U-value mean?
The material is a better insulator
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What is the U-value of a material equal to?
U-value of the material = energy/s passing per m2 for 1 C temperature difference
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## Other cards in this set

### Card 2

#### Front

What does the principle of conservation of energy state?

#### Back

That energy cannot be created or destroyed, it is only possible to change it from one form to another, or transfer it from one place to another

### Card 3

#### Front

Does the total amount of energy ever change?

### Card 4

#### Front

What two types of energy we get out of a machine consist of?

### Card 5

#### Front

What is useful energy?