Newton’s First Law of Motion: Inertia

Newton’s First Law of Motion “An object remains at rest, or in uniform motion in a straight line, unless compelled to change by an externally imposed force.”

In layman’s terms 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.

Still not sure? 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

Let’s Elaborate 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)

And the Scientists? 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?

Frictional Forces Resistive Forces – Opposing motion Friction and Air Resistance are the two common resistive forces

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

Let’s talk mass What is mass?

How is inertia related to 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.

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

WOULD YOU RATHER? INERTIA STYLE

Try to move: OR

Sumo Wrestle OR

Try to catch OR