1. 5.1 The Nature of Forces
Chapter 5: FORCES

2. WHAT IS A FORCE? Force- push or a pull
When one object pushes or pulls another object, we say that the first object exerts a force on the second object
Ex: I exert a force on a pen when I write.
Ex 2: I exert a force on the Gorilla when I pick him up.
Ex 3: I exert a force on my meter stick when I swing it.

3. BALANCED FORCES
Balanced Forces – all forces add up to zero and do NOT change the object’s motion
Forces are in the opposite direction
Ex: Tug of War
The rope does not move because there is a balanced force on the rope.
5 N
5 N

4. UNBALANCED FORCES
Unbalanced Forces – net force is NOT zero so the object will change motion
UNBALANCED
BALANCED
2 N
5 N
5 N

5. UNBALANCED FORCES + = + =
BALANCED FORCES + =

6. INERTIA Inertia – Object’s tendency to resist change in motion
Ex: A truck has a large amount of inertia… imagine trying to make it stop… it’s hard because the truck has a lot of inertia

7. NEWTON’S FIRST LAW An object at rest will remain at rest
An object in motion will remain in motion
UNTIL!!! Acted upon by an outside force.

8. MASS Mass – the amount of matter in an object
This is not the size of an object but how much mass it has
Ex: A bar of metal is going to have more mass then an equal sized bar of styrofoam

9. Homework Study for vocab quiz
Copy the diagram on page 145 of your textbook as the output on page ___ of your notebook
You must draw all of the arrows
You must copy all of the text