1. DO NOW Hand in “Acceleration and Slope Lab” in your class bin.
Open notebooks to take short notes on forces and motion. Title notes “Forces change motion”

2. Forces change motion
Chapter 2.1

3. Forces
Force: A push or pull; changes the motion of an object

4. Types of Forces
Contact Force: one object pushes or pulls another object by touching it
Gravity: force of attraction between two masses (Earth’s gravity)
Friction: resists motion between two surfaces that are pressed together

5. Balanced and Unbalanced Forces
Force is a vector: has both size and direction
Net Force: the overall force acting on an object when all the forces are combined
Balanced Forces: the net force is zero
Unbalanced Forces: one force is greater than the other(s)

6. Forces on Moving Objects
As long as forces are balanced, an object can move at a constant velocity.
Ex: riding your bike at a constant speed. If you stop pedaling, eventually your bike will come to a stop
An unbalanced force is needed to change an object’s motion.