Forces and Energy Changes: Work

Work is done when a force causes an object to move.
The amount of work done can be calculated using the equation: Work done = force x distance. The unit for work is joules (J).
Energy is transferred when work is done; this is because work requires energy.
If no movement occurs, there is no work done even if a force has been applied. For example, if you push a wall, you’re applying a force, but if the wall doesn’t move, you’re doing no work.
When work is done against the force of gravity (such as lifting an object), the work done is equal to the gravitational potential energy gained by the object.
If work is done to move an object at a steady speed against a frictional force, the work done is converted into heat energy.
The principle of conservation of energy states that energy cannot be created or destroyed, it can only be transferred from one form to another. So, keep in mind that work done will always result in energy being transferred or transformation.
The more work done on an object, the more energy gets transferred. Similarly, the larger the force or the greater the distance moved, the greater the work done.
Work done can also result in a change in kinetic energy. If the work done on an object makes it move faster, the object’s kinetic energy increases.
Energy transfers that involve work done are often not 100% efficient. Some of the energy may be lost as heat due to friction between moving parts. Efficiency can be improved by reducing friction, for example by lubrication.
To work out the energy transferred by work done, you may need to know the force applied (in newtons), the distance moved (in metres) and the direction of the force in relation to the direction of movement.