Work and Power
Work and Power
Understanding Work

Work is one form of energy transfer. When a force acts on an object to move it, work is being done.

It’s measured in joules (J).

The formula to calculate work is work (W) = force (F) x distance (d).

The force must be applied in the direction of movement for work to happen. If the force is perpendicular to the direction of movement, no work is done.

Work done is the product of the force exerted on an object and the distance it moves as a result. If the object does not move, no work is done.
Power and How It Relates to Work

Power is the rate of doing work or the amount of work done in a unit of time.

It’s measured in watts (W). One watt equals one joule per second (1 W = 1 J/s).

The calculation for power is power (P) = work done (W) / time (t).

The more work done in a certain period of time, the more power is required.

Oftentimes power is also defined as the rate of energy consumption or the rate at which energy is transferred.
Understanding Energy Efficiency

Energy efficiency refers to how effectively energy is converted from one form to another.

It is calculated by dividing the amount of useful energy or power output by the total energy or power input.

It can be represented as a decimal or a percentage. It’s a dimensionless quantity, meaning it has no units.

An efficient system has less energy wasted as unwanted output, usually thermal (heat) energy.

Knowing the work done and power used can help determine the efficiency of a system. Fewer joules of energy wasted for the same amount of work done means a more efficient system.

Contrariwise, the same amount of work done with more power used means the efficiency is lower. The extra energy has been wasted.