Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

The more mass a substance has the more force is required to move it or to change its direction. This resistance to changes in direction is known as inertia.

Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.

Potential energy is the energy of an object by virtue of its position relative to other objects. It is energy that has the potential to be converted into kinetic energy.

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.