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Work

Work is energy transferred when a force moves something. Only the force component along the motion does work. A force perpendicular to the motion, like the normal force on a flat floor, does no work.

W = F\,s\cos\theta

work done by a constant force

P = \frac{W}{t} = F\,v

power is work per time

Symbols

$W$	work	J
$F$	force	N
$s$	distance	m
$\theta$	angle between force and motion	°
$P$	power	W

Example

You pull a crate 10 m with 50 N at 30°:

$W = 50\cdot 10\cdot\cos 30^\circ \approx 433$ J.

Force and motion in the same direction give positive work, opposite directions (like friction) give negative work.

Practise work, energy and momentum for free →

← Cross-section and I-beam · Conservation of energy →

Part of Statics and Dynamics: Work, energy and momentum.