# 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.