## Sunday, 18 March 2012

### Work

Work is a measure of change of energy.

The net work done equals the change in Kinetic Energy (this is the Work-Energy Theorem).

Work is the integral of the scalar product (dot-product) of two vectors: Force and Displacement. "Displacement" means the change in position of the point at which the force is applied.

So Work is a scalar (an ordinary number), with dimensions of mass times distance-squared over time-squared.

The SI unit is the amount of Work done by a Force of one newton acting over a displacement of one metre, and is called the joule (J), or newton-metre (N-m).

Work is the integral of the dot product of force and displacement.

W=a+daFdr

For a constant force, work is the dot product of the force with the total displacement.

W=Fd.

The above work equals the magnitude of the force times the magnitude of the displacement times the cosine of the angle between the force and displacement:

W=Fdcos(θ).