Section 4 - Work And Power Flashcards
Explain how work done is just energy transferred.
Whenever something moves, something else is providing some sort of effort to move it.
I think putting the effort in need to supply of energy like fuel or food or electricity.
It then does work by moving the object, and one way or another it transfers the energy it receives as fuel into other forms.
Whether this energy is transferred usefully by lifting a load or is wasted lost as heat. You can still say that work is done.
When you do work against friction, most of the energy gets transformed into heat, and usually some into sound. This is generally wasted energy.
What happens when a force moves an object?
Energy is transferred and work is done.
Work done =
Force× distance moved
Whether the force is friction or weight or tension in a rope, it’s always the same. To find how much work has been done in Joules, you just multiply the force in newtons by the distance moved in metres.
What is power?
Power is the rate of energy transfer or the rate of doing work.
Power is not the same thing as force, nor energy. A powerful machine is not necessarily one which can exert a strong force. A powerful machine is one which transfers a lot of energy in a short space of time.
Power =
Work done / time taken
Power is measured in watts or J/s
The proper unit of power is watt. One watt = 1 joule of energy transferred per second. Power means how much energy per second, so watts are the same as joules per second.
