1. Newton’s 1st Law How would you explain this animation?
Demo: What happens to the stack of pennies?

2. Newton’s 1st Law
An object at rest or an object in motion at constant speed will remain at rest or at constant speed in the absence of a resultant force.
A glass is placed on a board and the board is jerked quickly to the right. The glass tends to remain at rest while the board is removed.

3. Understanding the First Law
Discuss what the driver experiences when a car accelerates from rest and then applies the brakes.
(a) The driver is forced to move forward. An object at rest tends to remain at rest.
(b) Driver must resist the forward motion as brakes are applied. A moving object tends to remain in motion.

4. INERTIA
Inertia is the tendency of the object to maintain its state of rest or of motion. Inertia is direct proportional to mass. More mass means more inertia, less mass means less inertia.
What happens to the blocks after the collision?

5. INERTIA Why is the pail with sand more difficult to be pushed?
Because it has more inertia.

6. INERTIA
Why does the carton of eggs inside a car on a curve appear to be moving outward?
Because of the inertia, it wants to maintain its previous straight-line motion.

7. Newton’s 1st Law
Why does penny drop inside the glass if the paper under it is quickly flicked?
Because of the inertia, the penny maintains its previous state of rest.