Newton's laws

Normal force

The perpendicular force exerted by a surface on an object in contact with it.

Frictional force due to a surface

The force that opposes the motion of an object and acts parallel to the surface with which the object is in contact.

Newtons first law

An object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force.

Inertia

The property of an object that causes it to resist any change in its state of rest or uniform motion.

Newtons second law

When a net force, Fnet, is applied to an object of mass, m, it accelerates in the direction of the net force. The acceleration, a, is directly proportional to the net force and inversely proportional to the mass.

Newton’s third law

When object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object A.