Work Done (AQA 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

Examples of Work

• Work is done on a ball when it is lifted to a height above the ground

The weight on the ball produced by the gravitational field does work on the ball over a distance equal to the height of the ball

• Work is done when a bird flies through the air

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

• 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
• To calculate the amount of work done on an object by a force the following formula is used

W = F × s

• Where:
  • W = work done in Joules (J) or newton-metres (N m)
  • F = force in Newtons (N)
  • s = distance in metres (m)

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

Step 1: List the known quantities

• • Distance, s = 23 m
  • Force, F = 500 N

Step 2: Write out the equation relating work, force and distance

Work = F × s

Step 3: Calculate the work done on the car by the brakes

Work = 500 × 23 = 11 500 J