Energy Equations

Efficiency equation relating to energy

Useful output energy transferred by the device

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Total input energy supplied to the device

Efficiency equation relating to power

Useful power out

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Total power in

Work done (J) (energy) equation

force applied (N) x distance moved (m)

Change in objects gravitational potential energy (J) store equation

mass (kg) x gravitational field strength (N/kg) x change of height (m)

Change in elastic potential energy (J) equation

½ x spring constant (N/m) x extension² (m)

Kinetic energy (J) equation

½ x mass (kg) x speed² (m/s)

power equation

Energy transferred to appliance (J)

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Time taken for energy to be transferred (s)

(elephants play tennis)

Power wasted by an appliance equation

total power input - useful power input