A demonstration of Newton's first law of motion.

A demonstration of Newton's second law of motion.

A demonstration of Newton's third law of motion.

Newton's three laws of motion are:
1. Every body continues in a state of uniform motion in a straight line unless acted upon by some external force. This is normally taken as the definition of inertia. Essentially, if there is no net force resulting from unbalanced forces acting on an object (if all the external forces cancel each other out), then the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. And if an additional external force is applied, the velocity will change because of the force.

2. The time rate of change of momentum (mass x velocity) is proportional to the impressed force. In the usual case where the mass does not change, this law can be expressed in the familiar form:

Force = mass x acceleration or F = ma.

A force will cause a change in velocity; and likewise, a change in velocity will generate a force.

3. To every force or action, there is always an equal and opposite reaction. If object A exerts a force on object B, then object B also exerts an equal and opposite force on object A.

Sir Isaac Newton first presented his three laws of motion in the "Principia Mathematica Philosophiae Naturalis" in 1686.