South Pasadena Physics Name

South Pasadena • Physics Name

4 · Forces Period Date

4.1 NOTES – INERTIA AND FORCES

Newton’s First Law

Aristotle and Motion

Natural Motion – the natural way objects move.

-  Objects move to the natural resting places: heavy things move down and light things move up. Planets move in perfect circles.

-  An object at rest does not move on its own.

Violent Motion – motion resulted from an external cause.

-  A force was involved if an object is moving against its natural motion.
No force = no motion.

Galileo and Motion

Idea #1

Idea #2

Inertia

Mass: a measure of inertia

Units:

Mass is a [ scalar | vector ] quantity.
Newton’s First Law: Law of Inertia

Forces

Defining Force

Remember acceleration?

Re-Thinking Gravity

“Force of Gravity” vs. “Acceleration due to Gravity”

Which one has a greater acceleration? Which one has a greater force? Why?

Newton’s Second Law

Units:

Force is a [scalar | vector ] quantity.

Mass vs. Weight