Power and Efficiency Notes

A set of vocabulary flashcards covering the definitions, units, and formulas for power and energy efficiency as presented in the lecture notes.

Power

The rate at which work is done or the rate of energy.

Watt

The unit of power, equivalent to $Js^{-1}$.

$$P = \frac{W}{T}$$

The formula for power where $P$ is power ($W$), $W$ is work done ($J$), and $T$ is time ($s$).

$$Power = Force \times velocity$$

An alternative expression for power, calculated by multiplying force ($N$) and velocity ($v$).

Efficiency (E)

A measure of how much useful work is done with the energy supply, often expressed as a percentage.

Efficiency (Work Formula)

$$\frac{\text{useful work done}}{\text{total work input}} \times 100\%$$

Efficiency (Energy Formula)

$$\frac{\text{useful energy output}}{\text{total energy input}} \times 100\%$$

Efficiency (Power Formula)

$$\frac{\text{useful power}}{\text{Total energy input}}$$