Understanding Work Done

Work done is the energy transferred by a force. It happens when a force moves an object in the direction of the force.
The formula for work done is Work done = Force x Distance, where ‘Force’ is in newtons (N), ‘Distance’ is in metres (m), and ‘Work done’ is in joules (J).
Note that no work is done if the force and displacement are perpendicular to each other, i.e if force is applied but the object does not move.

Real-life Examples of Work Done

Lifting an object against the force of gravity requires work. The work done equals the force required to lift it (which equals its weight) times the height it’s lifted.
For example, when you lift a book from the floor to a shelf, you’re doing work against the force of gravity.

When a force is applied to a spring or an elastic band, and it’s stretched or compressed, work is done against the object’s elasticity.
This causes elastic potential energy to be stored in the object, which can be calculated using the formula Elastic potential energy = 0.5 x spring constant x (extension)^2.
The spring constant (k) is a measure of the stiffness of the spring, while extension refers to how much extra length is added to the spring when force is applied to it.

The Principle of Conservation of Energy states that energy cannot be created or destroyed, only transferred from one form to another.
When work is done, the energy is transferred from one form (usually kinetic or potential energy) into another.
Remember, energy transferred = work done, and their units are both measured in joules (J).
The Efficiency of a system can also be calculated using the work done. Efficiency is the percentage of the input energy that is useful, calculated using the formula: Efficiency = (Useful energy output / Total energy input) x 100%.