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?

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 one 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 the force acting on the below object over a distance of 5m?

10 × 5 = 50 Nm

= 50 J

What occurs when work is done against frictional forces?

• a rise in temperature of the object occurs

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