Work

Work is done when a force acts over a distance. Its units are given in Newton-metres, or Joules (J). If force is variable and given as a function \vec{F} = f(x) (with x being the position), and b - a is the interval over which the force acts, work is given by
:W = \int^b_a f(x)dx
or more generally (as a vector line integral)
: \int_a^b \vec{F} \cdot d \vec{r}
If the force is constant and always parallel to the displacement vector, this simplifies to
:W = | \vec{F} | d or
==Formulae for work==
*W = -\Delta U, where U is potential energy
*W = \int^b_a P(t)dt = P_\mathrm{avg} t where P is power
*W = \int_{\alpha}^{\beta} \tau\, d \theta where τ is torque and θ is the angle across which torque is applied
*W = \tau \theta (if τ is constant)
*W = \frac{1}{2} k x^2 for a spring obeying Hooke's law
*W = \int^b_a P \ dV where P is pressure and a and b are initial and final volumes
Category:Mechanics