1. Section 2-3 Connecting Motion with Forces

2. What is a force?
Force- a push or pull one body exerts on another

3. Force changes the motion or shape of an object

4. Unbalanced force – when the forces on an object are unequal
Ex. Man pushing car
Result = motion

5. Balanced Force – forces on an object that are equal in size and opposite in direction

6. Balanced forces Example: sitting down
Chair
pushing up
Gravity
pulling
down
Result – forces are equal, no motion

9. Friction – the force between two surfaces that are touching each other.

10. Sliding Friction
Caused by two surfaces sliding past each other

11. Rolling Friction
Friction between a rolling object and the surface it rolls on.

12. Static Friction
Friction between two surfaces that are not moving past each other.

13. Life without Friction