Newton's Laws of Motion: Inertia, Force, and Action-Reaction

Newton's first law

An object in motion stays in motion unless acted upon by an outside force; an object at rest stays at rest.

- Law of Inertia

inertia

tendency of an object to resist changes in its state of motion.

How does mass affect inertia?

More mass results in more inertia.

Newton's Second Law

When an external force is applied to an object, it causes it to accelerate

- Law of Acceleration

Formula for Newton's second law

F = ma

- F is force, m is mass, a is acceleration.

How does force and mass affect acceleration according to Newton's second law?

An object's acceleration is directly proportional to the net force and inversely proportional to its mass.

difference in acceleration between a soccer ball and bowling ball

A soccer ball accelerates quicker than a bowling ball when pushed because it is lighter.

Newton's Third Law

For every action, there is an equal and opposite reaction; forces always occur in pairs.

- Law of Action & Reaction

Provide an example of Newton's third law in action.

A rocket pushes hot gas downward, and in response, the gas pushes the rocket upward.