Newton’s First Law of Motion:Inertia

“An object remains at rest, or in uniform motion in a straight line, unless compelled to

change by an externally imposed force.”

Newton’s First Law of Motion

Objects want to continue doing what they are already doing: Objects at rest will stay at rest Objects in motion will continue in that motion

(constant speed and direction) Unless an outside force acts on the object.

In layman’s terms

Unless there is a force acting on the object, its velocity will not change.

Unless there is a force acting on the object, it will remain at rest

Still not sure?

No change in speed or direction = CONSTANT VELOCITY

Objects at rest = ZERO VELOCITY These values remain constant in the absence

of a force. NO FORCE = NO ACCELERATION (because

the velocity does not change)

Let’s Elaborate

Aristotle believed that a force was required to keep an object in motion.

Chair Example vs. Projectile Example

Newton and Galileo made the statement that no force is needed to keep an object moving, but will a force prevent it from moving?

And the Scientists?

Resistive Forces – Opposing motion

Friction and Air Resistance are the two common resistive forces

Frictional Forces

http://www.youtube.com/watch?v=A6snX4M2_8U&feature=bf_prev&list=PLURSuaQhTHRnOYXl8sQp1NIDZ36fGtH43

What is Inertia?

What is mass?

Let’s talk mass

We refer to Newton’s First Law as the Law of Inertia

This is the objects resistance to a change in its motion.

So we can define mass as a measure of an object’s inertia, the property that cause it to resist a change in its motion.

How is inertia related to mass?

http://www.youtube.com/watch?v=SIsl1TQEcCA&feature=bf_next&list=PLURSuaQhTHRnOYXl8sQp1NIDZ36fGtH43

Inertia and Mass

WOULD YOU RATHER?INERTIA STYLE

Try to move:

OR

Sumo Wrestle

OR

Try to catch

OR