1. Motion and Forces:Newton’s First Law

2. What is a force? A force is defined as a push or a pull. You are aware of forces that cause things to move, but not always aware of forces that keep things in place, like gravity.

3. Changing Motion When a force is exerted on an object, it can cause it to change its motion. For example, if you hit a baseball with the bat, it changes direction. If you push an object that is not moving with enough force, it will move. The amount of force and the direction in which it is applied will determine the motion.

4. Net force When two or more forces act on an object, they create the net force. In this picture, the net force is zero. The forces are balanced and the fridge doesn’t move:

5. What happens if forces are unbalanced?

6. If forces are unbalanced, the object will move in the direction of the greater force. However, all objects have inertia, which is the tendency of an object to resist any change in motion. How does it do this? This brings us to Newton’s First Law…

7. “The Law of Inertia”

9. What happens in a crash?

10. The car stops moving because it hits another object ( a force acts on it), but the person driving the car continues moving forward. Thus the importance of seat belts, which provide a force which stops your motion!