Energy, Work and Power

• Energy: amount of work and its measured in Joules (J)

• Conservation of energy: energy cannot be created or destroyed, when work is done, energy is changed from one form to another.

  • Energy can be stored

• A book on a shelf has g.p.e , if it falls of the shelf it will have k.e

• Due to the processes through which energy transfers take place not being 100% efficient

• energy is lost to the surrounding and therefore energy gets more spread out (dissipated)

• Efficiency: how much useful work is done with energy supplied

Energy Resources

• Renewable sources: Energy sources that are not exhaustible/ Infinite

• Non-renewable sources: Energy sources that are exhaustible/ finite

Work and Power

• Work****: Work is done whenever a force acts on an object that moves (or is moving) in the direction of the force

  • The greater the force, the greater the work

  • The larger the distance moved, the larger the work

• Whenever any work is done, energy gets transferred (mechanically) from one form to another

• The amount of energy transferred (in joules) is equal to the work done (also in joules)

  • energy transferred (J) = work done (J)

Work done = Force x Distance travelled

• Power: is the rate at which a machine transfers energy

• The greater the rate at which energy is transferred, the greater the power

  • Because work done is equal to energy transferred, the power is also equal to the rate of doing work

• Power = Energy/time