P5: Work Done & Energy Transfer Physics GCSE

• What is work done when an object is moved?

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

  No work is done on the object
• How does gravitational force do work on a ball?

  It acts over the distance of the ball's height
• What does air resistance do when a bird flies?

  It works against the bird's motion
• What is the relationship between work done and force applied?

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

  W = F × s
• What does W represent in the work formula?

  Work done in Joules (J)
• What does F represent in the work formula?

  Force in Newtons (N)
• What does s represent in the work formula?

  Distance in metres (m)
• What are the units for work?

  Joules (J) or newton-metres (N m)
• How are Joules and newton-metres related?

  1 J = 1 N m
• What happens 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 in its kinetic store
• What happens if a force acts opposite to the movement?

  The object loses energy to the thermal store
• Calculate the work done when a force of 100 N lifts an object 10 m.

  $1000 \text{ N m} \text{ or } 1000 \text{ J}$
• What is the energy transfer when lifting a bucket from a well?

  Energy is transferred to the gravitational potential store
• How is work calculated for the bucket being lifted?

  Work = m × g × h
• Calculate the work done on the bucket when lifted.

  $1470 \text{ N m} \text{ or } 1470 \text{ J}$
• What is the relationship between changes in speed and energy?

  Changes in speed relate to kinetic energy
• What is the relationship between changes in height and energy?

  Changes in height relate to gravitational potential energy
• What is the relationship between changes in shape and energy?

  Changes in shape relate to elastic potential energy
• What does friction do to an object's motion?

  It works in opposition and slows down motion
• How does friction transfer energy?

  By heating, raising temperature of object
• What causes the rise in temperature due to friction?

  Work done against frictional forces
• What is air resistance?

  A type of friction that slows motion
• How does air resistance transfer energy?

  By heating due to work against friction
• What happens to a rocket's return module due to air resistance?

  It heats up from work done against air resistance
• How does friction affect energy transfer in motion?

  It converts kinetic energy to thermal energy