Newton’s Laws of Newton’s Laws of Motion Motion

Sir Isaac Newton

Born January 4, 1643 in England

As a young student, Newton didn’t do well in school.

He worked hard and continued his education.

Later in life, Newton contributed ideas that became law in the worlds of science and math.

Newton’s Law of Inertia

“An object at rest, tends to stay at rest, and an object in motion, tends to stay in motion with the same speed and in the same direction, unless acted upon by an outside force.”

Objects resist change in motion.The more mass an object has, the greater its inertia.

Newton’s Law of Force and Acceleration

F = ma Net force on object = mass of object x acceleration Which vehicle will accelerate more quickly? Why?

For Example…

If the force remains constant, smaller masses will have greater acceleration compared to larger masses.

If the force remains constant, larger masses will have less acceleration compared to smaller masses.

F=ma F=ma

For Example…

Small Mass = Greater Acceleration

Large Mass = Less Acceleration

Newton’s Law of Force and Acceleration

If the mass of an object remains constant, then acceleration increases as the force increases.

ALWAYS identify the force, mass, and acceleration variables to see which ones are constant.

Force

Force (N) = mass (kg) x acceleration (m/s2)

F = ma

So, what happens if you are trying to see how fast a force can accelerate a particular mass??

Write the initial equation:

F = ma

Decide what you are solving for:

acceleration

Use math to restructure the equation:

F = ma

m m

So, what happens if you are trying to see how fast a force can accelerate a particular mass??

The equation for acceleration is:

a = F

m

But does the equation make sense??

What happens to the acceleration of a bicycle if the force is increased (pedal harder)??

What happens to the acceleration of a bicycle if the mass is increased (having to pull friends on rollerblades)??

This can be done to find the mass of an object being accelerated with a particular force.

Write the initial equation:

F = ma

Decide what you are solving for:

mass

Use math to restructure the equation:

F = ma

a a

So, what happens if you are trying to see how fast a force can accelerate a particular mass??

The equation for mass is:

m = F

a

Does it make sense?

Newton’s Law of Action-Reaction

"For every action, there is an equal and opposite reaction."

Reaction

Action

Newton’s Law of Action-Reaction

All forces act in pairs.

When one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.

This is not a cause-effect relationship.

The forces occur simultaneously.