1. 3.1 Force, Mass and Acceleration
Newton’s First Law

2. Newton’s First Law
An object at rest will remain at rest unless acted on by an unbalanced force.
An object in motion will continue with constant speed and direction, unless acted on by an unbalanced force.

3. Force
If you teacher asked you to move a cart containing a large, heavy box, would you:
A. Push it
B. Pull it
C. Yell at it until it moved?
A. Push it or B. Pull it

4. Force, con’t
Force- what we call push or pull, or any action that has the ability to change motion.
We measure force in two units:
POUNDS
NEWTONS

5. How much do you weigh in Newtons????
(Your weight)= (Your weight) x 4.48N/1 LB

6. What IS the difference between force and mass?
POUNDS OR NEWTONS
GRAMS OR KILOGRAMS
PUSH OR PULLING ACTION THAT CHANGES MOTION
AMOUNT OF “STUFF” OR MATTER IN AN OBJECT.

7. Balanced Forces Force does not always change velocity
When two or more forces act on an object at the same time, the forces combine to form NET FORCES.
Forces on an object that are equal in size and opposite direction are called BALANCED FORCES.

8. Unbalanced Forces When two forces are not equal while being pushed
Can you think of an example?

9. Law of Inertia
Newton’s first law is also known as the “Law of Inertia”
Inertia: the property of an object to resist changing its state of motion.

10. Inertia
An object with a lot of inertia take a lot of force to start or stop!
The amount of inertia an object as, depends on its MASS.

11. Question
Which is harder to push, (1) a ball that has a mass of 1 kilogram, or (2)a ball that has a mass of 100 kilograms??
(2) a ball that has a mass of 100 kilograms.
Why?
It has more mass!