1. Chapter 4 - Laws of Motion
Notes 4.1a – Newton’s 1st Law

2. Objectives Define Newton’s First Law of Motion.
Explain how inertia and mass are related.
Define Newton’s Second Law of Motion.

3. Isaac Newton British Scientist
British Scientist
Published 3 rules in 1687 to explain how forces and motion are related
Rules apply to motion of all everyday objects as well as planets, stars and galaxies
That’s why we call it Universal Gravitation

4. Newton’s first law of motion
States that the motion of an object changes only if an unbalanced force acts on the object
If forces are balanced, object doesn’t change its motion
Only unbalanced forces change velocity

5. Inertia
Tendency of an object to resist a change in its motion
1st Law = LAW OF INERTIA

6. Inertia & mass Inertia varies with mass
Mass is a quantity which depends solely on inertia
More inertia = more mass
A more massive object has a greater tendency to resist changes in its state of motion

7. Inertia & your car Inertia explains what happens in a car crash
Car and your body are moving at the same speed
Brakes slow and stop car
Seat belts slow and stop your body
Seat belts loosen slightly to decrease the force acting on your body and increase the time it takes to slow your body (GOOD THING)

8. Newton’s 2nd Law
Describes how the forces exerted on an object, are related to its mass, and its acceleration.

9. Newton’s second law of motion
States that the acceleration of an object is in the same direction as the net force on the object, and that the acceleration can be calculated from the following equation:

10. Calculating Net Force
Newton’s second law also can be used to calculate the net force if mass and acceleration are known

11. In-Class Assignment/Homework
Article reading
Answer the questions on your lecture tutuorail and return article to front table
Pg. 103 #1-7