energy - work and power Flashcards
mechanical energy transfers, work, power, efficiency
what are 3 mechanical energy transfers
kinetic energy
gravitational potential energy
elastic potential energy
what is ‘work’
the process of transferring energy
what is the equation for work
if we have to apply a larger force or move for a larger distance, we are doing more work
work done = force x distance
w = fd
work = joules
force = newtons
distance = metres
what is power
the rate at which work is done
what is the equation for power
power = work done ÷ time taken
p = w/t OR p = e/t
power = watts
work = joules
time taken = seconds
what is efficiency
a measure of how much energy put into a device is transferred into a useful form
what is the equation for efficiency
efficiency = useful energy output ÷ total energy input
(power instead of energy can be used)
(multiplying by 100 gives a percentage)
what is the equation for elastic potential energy
epe = 1/2 X force x extension
epe = 1/2fe
