1. Objective SWBAT define Newton’s first law of motion and use it to explain the motion of objects.

2. Newton’s First Law of Motion An object at rest will remain at rest unless acted upon by an outside force. An object in motion will remain moving at the same speed unless acted upon by an outside force.

3. Quick Review What is a force? A force is a push or a pull.

4. Inertia Inertia is the tendency of an object to resist a change in its motion. Objects that are at rest won’t move unless force is applied. Objects that are moving will keep their same speed unless force is applied.

5. Check For Understanding A spaceship is flying through space, propelled from Earth by rocket boosters. When the fuel in the rocket boosters runs out, what will happen to the spaceship? A.It will run out of energy and slow down. B.It will speed up. C.It will keep moving forward at the same speed forever.

6. Friction Friction is the force that resists sliding motion between two touching surfaces. Friction is why objects eventually stop sliding on a surface.

7. Friction

8. Check For Understanding If someone is pushing you on a skateboard and then they stop pushing you, what will happen, and why? A.The skateboard will keep moving forward at the same speed forever. B.Inertia will make the skateboard slow down. C.Friction will make the skateboard slow down. D.Friction will make the skateboard speed up.