# Energy and efficiency

Mind Map by , created over 3 years ago

## Mind Map on Energy and efficiency, created by Imran Z on 03/12/2016.

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 Created by Imran Z over 3 years ago
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Energy and efficiency
1 Conservation of energy
1.1 Energy cannot be created or destroyed, only transferred
1.1.1 When energy is transferred, only part of it may be usefully transferred --> the rest is wasted
1.1.1.1 Wasted energy is transferred to its surroundings, which become warmer --> wasted energy becomes more spread out --> less usefel
1.1.1.2 Sankey diagram
1.1.1.2.1 Shows useful and wasted forms of energy
1.1.1.2.2 Shows how efficient an appliance is
2 Efficiency = useful energy out/total energy in x 100%
3 Usefulness of electrical appliances
3.1 Electrical appliances transfer energy at the flick of a switch
3.1.1 You can calculate how much energy is transferred
3.1.1.1 E = P x t
3.1.1.1.1 Amount of energy transferred from the mains electricity (kWh and J)
3.1.2 You can calculate how much the appliance costs to run
3.1.2.1 Total cost of bill = no. of kWh used x cost per kWh (rate)
3.2 Power is the rate at which the object transfers energy
3.3 Cost effectiveness
3.3.1 Getting the best value for money
3.3.2 Payback time is the time it takes for an appliance/installation to pay for itself in terms of energy savings
4 Efficiency = useful power out/total power in x 100%
5 Input energy = useful energy + wasted energy
6 Forms of energy
6.1 Stored energies
6.1.1 Gravitational potential
6.1.1.1 A falling object transfers g.p. to kinetic energy
6.1.2 Elastic potential
6.1.3 Chemical
7 Improving effiency
7.1 Reduce:
7.1.1 Friction (e.g. lubricating moving parts)
7.1.2 Electrical resistance (e.g. less resistant wires)
7.1.3 Noise due to vibrations (e.g. cut out noise)
7.1.4 Air resistance (e.g. streamline the shapes of moving objects)