 A force is a push or pull that can cause motion (speed up, slow down, stop, move, or change direction)  Force is measured in Newtons (N)  Force is measured using a spring scale

 When forces are balanced there is either: 1. No motion  Ex: stopped car at a stop sign 2. Constant Motion  Ex: setting your car on cruise control Object is already moving

 Balanced forces do not cause a change in motion.  The forces are equal. 10 N 10 N – 10 N = 0 N 10 N

 When forces are unbalanced there is a change in motion. 1. Moving in same direction  add forces together to get the net force. 2. Moving in opposite directions  subtract the forces to get the net force.

 The forces are NOT equal. 10 N 20 N – 10 N = 10 N 20 N 8 N6 N 8 N + 6 N = 14 N

3 N, right – 6 N, left = 3N, left

4 N, left – 10 N, right =6N, right

5 N, right + 10 N, right =15N, right