Work Done/Energy Transfers

• What does it mean if a force is said to do ‘work’?

  The force causes an object to be displaced
• What is the equation used to calculate work done?

  Work done = Force x Distance
• What are the appropriate units for work done, force, and distance?

  Work done (Joules), Force (Newtons), Distance (metres)
• What distance must be used when calculating work done?

  The distance moved along the line of action
• Under what circumstance is 1 joule of work done?

  When a force of 1 Newton causes 1 metre displacement
• How many Newton-metres are equal to 1 joule of energy?

  1 Nm = 1 J
• How much work is done by a force of 10 N over a distance of 5 m?

  50 J
• What occurs when work is done against frictional forces?

  Temperature rises and kinetic energy converts to heat
• Why does air resistance slow down a projectile?

  It does work against air resistance, converting energy to heat
• What are the effects of work done against frictional forces?

  • Rise in temperature of the object
  • Kinetic energy is converted to heat
• What happens to kinetic energy when air resistance acts on a projectile?

  • Kinetic energy is converted into heat
  • The object slows down