Work Done & Energy Transfer

Work done

• When a force causes an object to move through a distance, work is done on the object: a force does work when it causes a displacement
• Recall this equation:

$$W = F s$$

• $W$ work done in joules, J; $F$ force in N; $s$ distance moved along the line of action of the force, in m
• One joule of work is done when a force of one newton causes a displacement of one metre: 1 J $=$ 1 newton-metre (Nm)
• Worked example: pushing a box with a force of 50 N across 8 m of floor. $W = 50 \times 8 = 400$ J