5.2 Work done and energy transfer

Question 1

What does it mean when work is done to an object? (2)

Answer 1

When a force causes an object to move through a distance - the force does work by causing the displacement of the object.

Question 2

What is the equation for work done?

Answer 2

Work done (J) = force (N) x distance [moved along the force’s line of action] (m)

Question 3

When is 1J of work done? What does this mean? (1)

Answer 3

1 Joule of work is done when 1 Newton of force causes a displacement of 1 metre.

• 1J = 1Nm

Question 4

What occurs when work is done against frictional forces? (1)

Answer 4

Rise in temperature of the object [as kinetic energy transfers into thermal energy].

Question 5

What does air resistance do to a projectile? (1) Why? (2)

Answer 5

Air resistance causes the projectile to slow down; because work is done against the air resistance causing the kinetic energy to transfer into heat energy.