1. Linear Motion Unit 1 Part II Forces
Ask if can move forces and vectors to unit 2?

2. Objectives:
State Newton’s 1st law of motion and display an understanding of its applications
Understand the difference between net forces that cause acceleration and those that have a zero acceleration
Identify action-reaction pairs
Be able to use the equilibrium rule with forces

3. Newton’s 1st Law
Isaac Newton- History: 1665 started working on laws of motion, but not published until 1687 **Newton’s First Law** (Law of Inertia) An object in motion/rest stays in motion/rest until acted upon by an external force.

4. Inertia
Inertia-
Ex pg. 28: A hockey pucks sliding across the ice finally comes to rest. How would Aristotle have interpreted this behavior? How would Galileo and Newton have interpreted it? How do you interpret it?

5. Net Force
Net Force- Forces are exerted ON a body (Action) and is exerted BY another body (Reaction). Hammer/Nail Person/Grocery Cart Table/Book Box/Boat (vi = 0 m/s)

7. The Equilibrium Rule
If there is no movement on an object it is said to be at equilibrium.
OR if the object is maintaining a constant velocity (speed) it is at equilibrium.

10. Equilibrium of Moving Things
Rest is only 1 form of equilibrium.
An object at constant SPEED/VELOCITY is also at EQUILIBIRUM!!!
At constant speed an object has NO net forces acting on it.

11. The Moving Earth
Copernicus’s idea that the Earth was moving was a debated topic. Early estimates were that the Earth was moving 107,000 km/hr or 30 km/s to encircle the Sun. True/False. If a bird were to drop to get a worm in 1 second from 30 km away it would miss the worm. Why?