Work done and energy transfers

• 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?

  Give appropriate units.

  Work done = Force x 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
• What occurs when work is done against frictional forces?

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

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