1. Newton’s First Law of Motion

2. Newton’s 1st Law of Motion (also known as the law of inertia)
An object at rest will remain at rest unless an unbalanced force acts upon it
Objects do not change their motion unless a force acts on them

3. First we need to define the word FORCE:
The cause of motion (what causes objects to move)
What are the forces?
Pushes
Pulls
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4. Objects at Rest
Objects at rest tend to stay at rest unless acted upon by a force. [push or pull]
Inertia can be described as the tendency of an object to keep doing whatever’s it’s doing: moving or not moving

5. Which vehicle has more inertia?
Mass & Inertia
Mass is the amount of matter in an object.
The more MASS an object has, the more INERTIA the object has. Less mass=less inertia
Bigger objects are harder to start & stop
Which vehicle has more inertia?
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6. What about objects that are already in motion?
An object moves in a straight line with constant speed unless a force acts on it. Objects do not change their motion unless a force acts on them

7. Newton’s 2nd Law of Motion
The net force on an object is equal to the mass of the object multiplied by its acceleration
Formula: F=m X a
Force is measured in Newtons (N) which is a kg-m/ s/ s
Mass is measured in kilograms (kg)
Acceleration is measured in meters per second per second (m/s/s or m/s2

8. Acceleration
Acceleration is ANY change in the motion which includes: -speeding up -slowing down -turning

9. Newton’s 3rd Law of Motion
If one object exerts a force on a second object, the second object exerts a force of equal strength in the opposite direction on the first object.
For every action there is an equal and opposite reaction

10. Examples of 3rd Law Rocket launching off launch pad
Can you think of some
more?

11. END for Newton’s Laws

12. Net Force
The net force on an object is the total amount of forces acting on the object.
20N
10N
Net force=20N right-10N left
Net force is 10 N to the right

13. Forces may be balanced or unbalanced
Balanced forces – net force is equal to zero so there is NO MOVEMENT
20N
20N
Subtract the two forces because they are in opposite directions
20 N to the right – 20 N to the left= 0

14. Unbalanced forces – Net force is greater than zero so there is MOVEMENT
Add the two forces because they are in the same direction
20 N to the right + 10 N to the left= 30 N to the right

15. The truck is in motion. What is the force that causes it to stop?
The push of the stopped car.
The car is at rest. What is the force that causes it to move?
The push of the truck.
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