1. Inertia - Newton’s First Law
Lesson 3:
Inertia - Newton’s First Law

2. Newton’s First Law of Motion
Objects at rest will stay at rest, and objects in motion will stay in motion, unless they are acted on by an outside force.
This scientific law is also known as the Law of Inertia.

3. Inertia is an object’s resistance to any change in its state of motion.

4. Inertia in Action
Place an empty cup on the table with an index card and coin on top as shown.
What do you think will happen when you flick the index card?

5. What happened to the coin when you flicked the index card?
What do you think caused this result?
Were you surprised by the result?

6. Discovery Education Video Science Video Vocab: Inertia

7. What outside forces affect the motion of objects on earth?
1. Gravity
2. Friction

8. Gravity is a force that exists between any two objects that have mass.
Earth’s gravity pulls objects toward the center of earth.
Earth’s gravity pulls objects with a force of 9.8 meters per second squared.

9. Friction is a force that opposes the motion of a body across a surface or through a gas or liquid.
Different surfaces exert different amounts of friction. It’s easier to slide across ice than to slide across concrete.
Friction on a moving object caused by contact with air molecules is called drag, or air resistance.

10. Discovery Education Video:
Playing With Inertia

11. Feather and Hammer on Moon
Teacher Tube Video:
Feather and Hammer on Moon

12. Key Questions
Roll a ball across three surfaces and describe the force of friction created by each surface. Which surface created the most friction? Why?
Where do you think would be the best place to observe the concept of inertia? Why?
Will two objects of different masses always fall at the same speed when dropped? Explain your answer.