3.3.1 Work and conservation of energy

Work done is defined as the product of force and distance moved in the direction of the force. We can use the following equation to determine work done:

W = F x

(at an angle: W = F x cosθ)

It has the unit Nm. 1 Nm = 1J. One Joule is defined as the work done when a force of 1 N moves its point of application 1 m in the direction of the force.

It is important to understand that work done = energy transferred (this is because energy is defined as the capacity to do work). Energy is a scalar quantity with the unit Joule. The energy of all systems with mass can be classified as kinetic energy (energy due to the movement of an object) and gravitational potential energy (the energy due to the position of an object in the Earth's gravitational field). 

It is imperative to understand that the total final energy is always equal to the total initial energy. This can be represented in the principle of conservation of energy: the total energy of a closed system remains constant, energy can never be created nor destroyed but can be transferred from one form to another.