Physics: Problems and Solutions

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 (with x being the position), and b - a is the interval over which the force acts, work is given by

or more generally (as a vector line integral)

If the force is constant and always parallel to the displacement vector, this simplifies to


Formulae for work[]

  • , where U is potential energy
  • where P is power
  • where τ is torque and θ is the angle across which torque is applied
  • (if τ is constant)
  • for a spring obeying Hooke's law
  • where P is pressure and a and b are initial and final volumes