1. Newton’s Laws of Motion
I. Inertia
II. F=ma
III. Action-Reaction Forces

2. Isaac Newton Sir Isaac Newton 1642 – 1727 Scientist and Mathematician
He defined the laws of motion and universal gravitation, which he used to predict precisely the motions of stars, and the planets around the sun. He published the laws in his book Philosophiae Naturalis Principia Mathematica (Mathematic Principles of Natural Philosophy) in 1687.
“If I have ever made any valuable discoveries, it has been owing more to patient attention, than to any other talent.” Sir Isaac Newton

3. Four Forces
Electromotive (EMF) Magnetism Gravity Friction/Air Resistance

4. But there are more….
Applied – The force an object exerts on another object.
Spring – The force of a spring pushing or pulling on an object.
Tension- The force a rope or cord puts on an object
Normal – The force a surface applies upward
on an object

5. Forces and Newton’s Laws
Newton’s three laws of motion affect all these forces.

6. While most people know what Newton's laws say, many people do not know what they mean (or simply do not believe what they mean).

7. Metric Force A force is a push or a pull.
The metric unit of force is the Newton (N), named after Sir Isaac Newton.
It is equal to 1 kg-m/s/s.
It is a force of about ¼ a pound – like a stick of butter.

8. What is meant by a balanced force?
If the forces on an object are equal and opposite, they are said to be balanced, and the object experiences no change in motion.

9. What is meant by an unbalanced force?
If they are not equal and/or not opposite, then the forces are unbalanced and the motion of the object changes.

10. Net Force: A combination of ALL the forces acting on an object
Net Force: A combination of ALL the forces acting on an object. If net force is 0: no movement If net force is not zero: movement will occur

11. First Law of Motion
The first law of motion states: If no net force acts on it, there’s no acceleration:
an object at rest remains at rest and
an object in motion remains in motion in a straight line at a constant velocity
It will keep on keepin’on

12. Newton’s 1st Law of Motion: AKA: The Law of Inertia
Remember:
The greater the mass of an object the greater the inertia

13. Newton’s First Law is also called the Law of Inertia
Inertia: the tendency of an object to resist changes in its state of motion
The First Law states that all objects have inertia. The more mass an object has, the more inertia it has (and the harder it is to change its motion).

14. 1st Law
Inertia is the tendency of an object to resist changes in its velocity - whether in motion or motionless.
These pumpkins will not move unless acted on by an unbalanced force.

15. What does this mean?
This means that there is a natural tendency of objects to keep on doing what they're doing.

16. Examples:
Soccer
If I kick a soccer ball towards the net and the goalie is not there to stop it…
GOAL!!!
Bowling
When I roll the ball
down the lane, it will
keep going until it hits
the pins… or the gutter!

17. Example: Two teams are playing tug of war. They are both exerting
equal force on
the rope in
opposite
directions. This
balanced force
results in no
change of motion.

18. Example: A powerful locomotive begins to pull a long line of boxcars
that were sitting at rest. Since
the boxcars are so massive, they have a
great deal of inertia and it takes a large
force to change their motion. Once they
are moving, it takes a large force to stop them.

19. Foucault Pendulum
On the top right is the Foucault Pendulum at the Pantheon in Paris, France.
Inertia keeps a pendulum swinging in the same direction regardless of the motion of the earth. This can be used to measure the motion of the earth. As the Foucault Pendulum swings it appears to be rotating, but it is the earth that is rotating under it.

20. Unless acted on by an unbalanced force (such as a golf
club or the wind) the
ball would sit on the
tee forever!

21. Unless acted on by an unbalanced force such as gravity and air resistance (fluid friction), once airborne,
the ball would never stop!

22. It’s forces we cannot see…
Why?
Why then, do we observe every day objects in motion slowing down and becoming motionless seemingly without an outside force?
It’s forces we cannot see…

23. Things don’t keep moving forever because there’s almost always an unbalanced force acting upon it.
A book sliding across a table slows down and stops because of the force of friction.
If you throw a ball upwards it will eventually slow down and fall because of the force of gravity.

24. In outer space, away from gravity and any sources of friction, a rocket ship launched with a certain speed and direction would keep going in that same direction and at that same speed forever.

25. Newtons’s 1st Law and You
Because of inertia, objects (including you) resist changes in their motion. When the car going 65 m/hour is stopped by the brick wall, your body keeps moving at 65 m/hour.
Don’t let this be you. Wear a seat belt!

26. How does Newton’s 1st Law Relate to Your Life?
Transporting something in the bed of a truck:
Think about riding a bike:
(Don’t try this at home…duh) Think about riding ON a car:
Riding a motorcycle:
Wearing seatbelts
Expensive & OUCH!: