Work done and power

• Work done


  Energy transferred to an object when a force is applied and it moves
• Work done on an object

  Depends on the size of the force and how far the object is moved in the direction of the force
• One joule of work is done when a force of 1 newton causes an object to move 1 metre in the direction of the force
• Calculating work done


  Work done = force (N) x distance moved in the direction of the force (m)
• Power


  The rate of energy transfer, measured in watts (W)
• You do the same amount of work running up the stairs as you walked up because the force and the distance are the same
• It is harder to run up the stairs because you are transferring energy more quickly
• Calculating power


  Power = work done / time
• To calculate the work done you need to multiply the force by the distance
• Work done


  Is measured in joules (J)
• Power


  Is the rate of work done
• It takes 40 seconds to lift the car
• Comparing work done and power

  1. Competitor 1: Pull distance = 30 m, Time = 30 s

  2. Competitor 2: Pull distance = 30 m, Time = 35 s
• The winner has the shortest time