1. 4.2 Newton’s Laws of Motion

2. Sir Isaac Newton ( )
Discovered laws of motion and gravity

3. Newton's Laws of Motion
First Law: An object at rest stays at rest and an object in motion, stays in motion (same direction & same speed) unless acted upon by an unbalanced force
Also called the Law of inertia

4. Inertia is a property of matter that causes it to resist any change in its motion
more mass = more the inertia
more speed = more the inertia

5. What is a Force? FORCE = Any push or pull acting on an object
Force is measured in Newtons.

6. Newton's Laws of Motion
Second Law: The acceleration of an object is proportional to the net outside force acting on the object
Force = mass object  acceleration of object
Formula: F = ma

7. Forces can be BALANCED or UNBALANCED
Balanced forces are equal in size and opposite in direction
Unbalanced forces are not equal in size and/or opposite in direction.
If the forces on an object are unbalanced, we say there is a NET force.

8. The greater the force, the greater the acceleration
The greater the mass, the greater the force needed for the same acceleration

9. Examples of Newton’s 2nd Law
Bunting the baseball, versus a grand slam
The positioning of football players - massive players on the line, lighter (faster to accelerate) players in the backfield
Pushing a loaded versus an unloaded truck

10. Newton's Laws of Motion
Third Law: For every force, there is always an equal and opposite reaction force.

11. Example of Newton’s 3rd Law

12. Weight: a measure of the gravitational force between two objects
Weight = (mass) x (acceleration due to gravity)
Formula: W = mg
more mass = more weight

13. How is mass different from weight?
Mass – the amount of matter in an object
Weight – the force that acts on the object

14. Weightlessness – free from the effects of gravity?

15. There is gravity in space
Weightlessness is due to a constant state of free-fall