Chapter 4: Newton's Laws of Motion

Force

Force

Force is a vector quantity and is a push or a pull

Normal force

The normal force is exerted on an object by any surface with which it is in contact

Friction force

the friction force exerted on an object by a surface acts parallel to the surface, in the direction that opposes sliding.

Tension force

The pulling force exerted by a stretched rope or cord on an object to which it’s attached is called a tension force.

Weight

The gravitational force that the earth exerts on your body is called your weight.

Newton’s first law of motion

A body acted on by no net force moves with constant velocity (which may be zero) and zero acceleration

One newton

One newton is the amount of net force that gives an acceleration of 1 meter persecond squared to a body with a mass of 1 kilogram

Newton’s second law of motion

If a net external force acts on a body, the body accelerates. The direction of acceleration is the same as the direction of the net force. The mass of the body times the acceleration of the body equals the net force vector.

Newton’s third law of motion

If body A exerts a force on body B (an “action”), then body B exerts a force on body A (a “reaction”). These two forces have the samemagnitude but are opposite in direction.