Mechanical work

A force acting through a distance does mechanical work. This transfers energy to the object's kinetic store, so it speeds up. The supplying store depends on the arrangement: it might be the chemical store of a fuel or the gravitational potential store of a falling mass.

When a force moves an object, it can transfer energy by mechanical work. Push a book upwards and the book–Earth system gains energy in its gravitational potential store. Stretch a spring and its elastic potential store increases.