1. IF YOU ARE SITTING STILL IN YOUR SEAT ON A BUS THAT IS TRAVELING ON A HIGHWAY, IS YOUR BODY AT REST OR IN MOTION?

2. NEWTON’S FIRST LAW OF MOTION An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force.

3. OBJECTS AT REST  An object that is not moving is said to be at rest.  Newton’s first law says that objects at rest will stay at rest unless they are acted on by an unbalanced force.  So, objects will not start moving until a push or a pull is exerted on them.

4. OBJECTS IN MOTION  An object that is moving is said to be in motion.  Newton’s first law says that objects in motion will stay in motion unless they are acted on by an unbalanced force.  So, objects continue to move until a push or a pull is exerted on them.

5. FRICTION & THE 1 ST LAW OF MOTION Friction: the force on objects due to the objects rubbing against each other.  Because of friction, the motion of objects changes.  The force of friction is opposite the force of motion. https://www.youtube.com /watch?v=II6hP0Wxle8

6. INERTIA def: the tendency of all objects to resist any change in motion.  Newton’s 1 st Law of Motion is sometimes called the Law of Inertia. Because of inertia:  you slide toward the side of a car when it turns a corner.  why it is impossible for a plane, car, or bicycle to stop immediately.

7. MASS & INERTIA  Mass is a measure of inertia.  Objects with small mass have less inertia than large-mass objects. (changing the motion of small-mass objects is easier than changing motion of large-mass objects)

8. WHY IS THE ROCK NOT MOVING? Because the woman cannot make an unbalanced force due to Friction & Inertia!

9. NEWTON’S FIRST LAW OF MOTION  Video Recap  https://www.youtube.com/watch?v=sabH4bJsxW A https://www.youtube.com/watch?v=sabH4bJsxW A  You can stop the video at 2:30