why are useful devices useful for
transferring energy to one store to another
what happens the less energy is wasted
the more efficient it is
how can you improve the efficiency of energy transfers
insulating, lubricating or streamlining objects
how do you calculate efficiency
useful power output/ total power input
what do you need to remember about useful energy output and total energy input
no device is 100% efficient and wasted energy is usually transferred into thermal energy stores
electric heaters are the only exception
why are electric heaters the only exception
all the energy in electrostatic energy is useful