Energy, work and power

Four fundamental quantities of mechanics in one place:

$E_k=\tfrac12 mv^2 \qquad E_p=mgh \qquad W=F\cdot s\cdot\cos\alpha \qquad P=\frac{W}{t}$

Kinetic energy $E_k$ depends on the mass and the square of the speed; potential energy $E_p$ — on the height above the reference level. Work $W$ is the product of force and displacement (taking into account the angle between them), while power $P$ tells you how fast work is done. The unit of energy and work is the joule (J); of power — the watt (W).