5.2 Work Done and Energy Transfers

• Work done by a force

  The force causes an object to be displaced through a distance
• Calculating work done


  1. Work done = Force x Distance

  2. Work done (Joules)

  3. Force (Newtons)

  4. Distance (metres)
• Distance used when calculating work done

  The distance that is moved along the line of action of the force
• 1 joule of work is done when a force of 1 Newton causes a displacement of 1 metre
• Relationship between Joules and Newton-metres

  1 Nm = 1 J
• Work done against frictional forces

  • Rise in temperature of the object
  • Kinetic energy converted to heat
• Air resistance slowing down a projectile

  • The object does work against the air resistance
  • Kinetic energy converted to heat, slowing down the object