ABSTRACT

At the end of this chapter you should be able to:

• define force and state its unit • appreciate ‘gravitational force’ • state Newton’s three laws of motion • perform calculations involving force F = ma • define ‘centripetal acceleration’

• perform calculations involving centripetal

force = 2mv

r • define ‘mass moment of inertia’

Thus, if a person is taken as one object and the Earth as a second object, a force of attraction exists between the person and the Earth. This force is called the gravitational force, (first presented by Sir Isaac Newton), and is the force that gives a person a certain weight when standing on the Earth’s surface. It is also this force that gives freely falling objects a constant acceleration in the absence of other forces.