Edexcel iGCSE Physics -4.11 Work Done by a Force- Study Notes- New Syllabus

Work Done by a Force

Work done is the energy transferred when a force causes an object to move in the direction of the force. Work is done only if the force produces movement.

Relationship Between Work Done, Force and Distance

The work done by a force is given by:

\( \mathrm{work\ done = force \times distance\ moved} \)

\( \mathrm{W = F \times s} \)

• \( \mathrm{W} \) = work done (joule, J)
• \( \mathrm{F} \) = force (newton, N)
• \( \mathrm{s} \) = distance moved in the direction of the force (metre, m)

1 joule is the work done when a force of 1 newton moves an object through a distance of 1 metre.

Important Conditions

• The force and movement must be in the same direction.
• If there is no movement, no work is done.
• If the force is perpendicular to the motion, no work is done by that force.

Example: Carrying a heavy bag horizontally does no work on the bag, because the lifting force is vertical and the movement is horizontal.

Work Done and Energy Transfer

• Work done = energy transferred.
• Doing work increases or decreases an energy store.
• For example, pushing an object increases its kinetic energy.

Key Idea

• A force must cause movement to do work.
• Bigger force or larger distance means more work done.
• Work done is measured in joules.

Important Points to Remember

• Always use distance moved in the direction of the force.
• Use SI units: N, m, J.
• Work done is a scalar quantity.