know the units for
Mass = kilogram (kg)
energy = joule (J)
velocity = metre/second (m/s)
acelleration = metre/ second 2 (m/s2)
force = newton (N)
time = second (s)
power = watt (W)
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Energy Stores: Chemical – e.g. the food we eat Kinetic – movement energy Gravitational – objects that are lifted up Elastic – e.g. from springs Thermal – from hot objects Magnetic – objects in magnetic fields Electrostatic – charged objects Nuclear – stored within a nucleus
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In any process energy is never created or destroyed. (It is just transferred from one store to another.)
The energy flow is shown by arrows whose width is proportional to the amount of energy involved. The wasted and useful energy outputs are shown by different arrows.
Gravitational potential energy (J) = Mass (kg) x gravitational field strength (N/kg) x height (m)
Kinetic energy (J) = 0.5 x mass (kg) x velocity (m/s) 2
Because energy is conserved the decrease in GPE = increase in KE, for a falling object if no energy is lost to the surroundings
