Work & Energy (Edexcel GCSE Physics: Combined Science)

• Work is done when an object is moved over a distance by a force applied in the direction of its displacement
  • It is said that the force does work on the object
  • If a force is applied to an object but doesn’t result in any movement, no work is done

Work is done when a force is used to move an object

• The amount of work that is done is related to the size of the force and the distance moved by the object in the direction of the force

Work done = energy transferred

• To calculate the amount of work done or energy transferred for an object, the following formula is used

• Where:
  • E = work done or energy transferred in joules (J) 
  • F = force in newtons (N)
  • d = distance in metres (m)

• This equation can be rearranged with the help of a formula triangle

Work done, force, distance triangle

• Work is done on a ball when it is lifted to a height 
  • The energy is transferred mechanically from the ball's kinetic energy store to its gravitational potential energy store

The weight on the ball produced by the gravitational field does work on the ball over a distance

• Work is done when a bird flies through the air
  • The bird must travel against air resistance, therefore energy is transferred from the bird's kinetic store to its thermal store and dissipated to the thermal store of the surroundings

Air resistance (drag) does work against the bird as it flies through the air