Work Done and Power – GCSE Physics A (Combined) OCR Revision

Work done is the energy transferred when a force moves an object.
It is measured in joules (J), which is the unit for energy.
The formula for calculating work done is force x distance.
The force must be in the same direction as the movement of the object for work to be done.
When the force is not in the direction of motion, you only consider the component of the force that is in the direction of motion.

Power is the rate at which work is done or energy is transferred.
Power is measured in watts (W) where one watt is equal to one joule of work done or energy transferred per second.
The formula for power is work done / time or energy transferred / time.
A machine that is more powerful than another does the same amount of work in less time.

Understanding the concept of work done is essential in understanding how much energy is being transferred in different situations, such as lifting a heavy object or pushing a car.
Understanding the concept of power helps to know how efficient a machine or process is, enabling us to make more energy-efficient choices in real-life situations.
An understanding of work done and power can also explain the functioning of various machines and systems, like engines and power plants.

Always make sure to use the correct units when carrying out calculations - force in newtons (N), distance in metres (m), work done in joules (J), power in watts (W) and time in seconds (s).
In scenarios where force and displacement are at angles to each other, remember to resolve the force into its components.
Ensure you understand the difference between work done (the energy transferred) and power (the rate of energy transfer).