Energy Resources and Transfer: Work and Power
Energy Resources and Transfer: Work and Power

Work, in terms of physics, is a calculated value of the force applied to an object and the distance that object moves in the direction of the force, given by the formula: Work = Force x Distance.

The unit of work is the Joule (J), where one Joule is the work done or energy transferred when one Newton of force moves an object by one metre in the direction of the force.

Power is the rate at which work is done or energy is transferred. It’s calculated by dividing the total amount of work done or energy transferred by the time taken. Power = Work done / Time taken.

The unit of power is Watt (W), where one Watt is equivalent to work done at a rate of one Joule per second.

For a fixed amount of work, the longer the time taken, the less power is used. Conversely, the shorter the time, the more power is used.

Practical examples of work and power can include lifting weights (where work is done against the force of gravity), or an engine doing work to move a car.

Devices that are more powerful are capable of transferring the same amount of energy in a shorter amount of time. For example, a powerful car engine would be able to accelerate a car to a certain speed in less time than a less powerful engine.

The efficiency of a device can be calculated by comparing the useful power output to the total power input, and is often expressed as a percentage.

For electrical devices, power (P) can also be calculated using the formula P = IV, where I is the current in Amperes (A) and V is the voltage in Volts (V).

Energy cannot be created or destroyed, only transferred or transformed, as stated in the principle of Conservation of Energy. This principle is important when understanding energy resources and how they are utilised in devices and systems.