5.2

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


  The force causes an object to be displaced through a distance.
• 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?


  It must be the distance that is moved along the line of action of the force.
• Under what circumstance is 1 joule of work done?


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


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


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


  A rise in temperature of the object occurs and kinetic energy is converted to heat.
• Why does air resistance slow down a projectile?


  The object does work against the air resistance, converting kinetic energy into 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 work is done against air resistance?


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