5.2 Work Done & Energy Transfer

• What is work done when an object is moved?

  When a force moves it over a distance
• What happens if a force is applied but there is no movement?

  No work is done
• What does the weight of a ball do when lifted?

  It does work over the height distance
• How does a bird flying through the air relate to work done?

  Work is done on the bird as it flies
• What does air resistance do to a flying bird?

  It does work against the bird
• What is the relationship between work done, force, and distance?

  Work is related to force size and distance
• What is the formula for calculating work done?

  W = F × s
• What do the variables in the formula W = F × s represent?

  W is work, F is force, s is distance
• What are the units for work done?

  Joules (J) or newton-metres (N m)
• How is work measured in joules related to newton-metres?

  1 J = 1 N m
• What happens to energy when work is done?

  Energy is transferred from one store to another
• What is the effect of a force acting in the direction of movement?

  The object gains energy
• What happens when a force acts opposite to the movement?

  The object loses energy
• What is the work done when lifting an object with a force?

  It is equal to the weight of the object times height
• How is the work done calculated when lifting a bucket?

  Work = m × g × h
• Calculate the work done on a bucket with mass 10 kg lifted 15 m.

  1470 N m
• What is the relationship between changes in speed and kinetic energy?

  Changes in speed relate to kinetic energy
• What does friction do to the motion of an object?

  It works in opposition and slows it down
• How does work done against friction affect temperature?

  It raises the temperature of the object
• What causes energy transfer to the thermal store?

  Work done against frictional forces
• What is air resistance in relation to friction?

  It is a type of friction that slows motion
• How does air resistance affect energy transfer?

  It transfers energy by heating
• What happens to a rocket's return module due to air resistance?

  It heats up from work done against air resistance