1. NEWTON’S LAWS OF MOTION
Chapter 20 section 2 page 550
NEWTON’S LAWS OF MOTION

2. OBJECTIVES
Describe Newton’s first law of motion, and explain how it relates to objects at rest and objects in motion.
State Newton’s second law of motion, and explain the relationship between force, mass, and acceleration.
State Newton’s third law of motion, and give examples of force pairs.

3. Newton’s First Law of Motion
An object at rest remains at rest, and an object in motion remains in motion at a constant speed and in a straight line unless acted on by an unbalanced force.

4. Part 1: Objects at rest Will not move unless something moves it.
It is balanced until an unbalanced force acts on it.

5. Part 2: Objects in Motion
Things will move in the same direction.
Things will move at the same speed
Unless an unbalanced for acts on it.

6. Inertia and Newton’s 1st Law
Newton’s 1st Law is sometimes called the LAW OF INERTIA.
Inertia – the tendency of all objects to resist any change in motion.

7. Mass and Inertia More mass = more inertia = harder to move
Less mass = less inertia = easier to move

8. Newton’s Second Law of Motion
The acceleration of an object depends on the mass of the object and the amount of force applied.

9. Part 1: Acceleration Depends on Mass
An empty cart has less mass than a full cart.
It is easier to accelerate.
Acceleration as mass
Acceleration as mass

10. Part 2: Acceleration Depends on Force
more force = more acceleration
Less force = less acceleration

11. Newton’s 2nd Law Mathematically
a = Acceleration
m = mass
F = force
a = F or F = m x a m

12. Newton’s Third Law of Motion
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.

13. 3rd Law All forces act in pairs.
As the swimmer’s hands push down on the water, the water pushes back on the swimmer’s hands.

14. 3rd law
As the person pushes against the springs, the springs push against the person

15. 3rd Law
The space shuttle’s thrusters push the exhaust gases down as the gases push the shuttle up with equal force.

16. YOUR TURN
Do the Chapter 20 section 2 Review on page # 1 - 9