1. Have you ever stopped to look at a car accident?

2. When you look at a car accident you are looking at the results
of the Forces of Motion around us.
Newton’s Laws of Motion

3. First we need to define the word FORCE:
REVIEW
First we need to define the word FORCE:
The cause of motion (what causes objects to move)
Two types of forces
Pushes
Pulls

4. Forces are measured in Newtons
REVIEW
Forces are measured in Newtons
SI unit of force
Symbol: N
Measured by using a spring scale

5. Forces may be balanced or unbalanced
REVIEW
Forces may be balanced or unbalanced
Balanced forces – all forces acting on an object are equal
There is NO MOTION
Unbalanced forces – one or more forces acting on an object are stronger than others
There is MOTION
A NET FORCE

6. Newton’s Laws First Law – Inertia
Second Law – Acceleration, Force & Mass
Third Law – Action-Reaction

7. This is the principle of inertia.
Law # 1:
Every object at rest remains at rest and every object in motion continues moving in a straight line at a steady rate unless a force acts it on.
This is the principle of inertia.
Can you tell me how this principle applies to car accidents?

8. First Law Inertia & Mass Mass is the amount of matter in an object.
The more MASS an object has, the more INERTIA the object has.
Bigger objects are harder to start & stop.

9. This is the principle of accelerated motion.
Law # 2
The amount of force needed to change the speed of an object depends on the mass of the object and the amount of acceleration (or deceleration) needed.
This is the principle of accelerated motion.
Can you tell me how this law applies to car accidents?

10. Second Law Acceleration & Force Acceleration & Mass
The more force placed on an object, the more it will accelerate [change its motion].
Acceleration & Mass
The more mass [or inertia] an object has, the more force it takes to accelerate the object.

11. Second Law Force = Mass x Acceleration
Example: A 25 g object with an acceleration of 4 m/s2 will have a force of ______ Newtons.

12. Forces come in pairs, called action-reaction pairs.
Law # 3
For every action there is an equal and opposite reaction. When an object is pushed or pulled by a force in one direction, another force pushes or pulls on it with equal strength from the opposite direction.
Forces come in pairs, called action-reaction pairs.
How does this law apply to car accidents?

13. Third Law Action – Reaction
Forces are always produced in pairs with opposite directions & equal strengths.
For every force there is an equal and opposite force.

14. Third Law Action – Reaction
Action – Reaction Forces act on different objects…
When you kick a soccer ball, you exert a force on the ball and the ball exerts a force on you. The harder you kick the bigger the force on you (kicking REALLY hard might hurt.)

15. Third Law

16. A swimmer pushes water back with her arms, but her body moves forward.
Which Law?
A swimmer pushes water back with her arms, but her body moves forward.

17. Newton's third Law
Action-Reaction

18. Which Law?
A frog leaping upward off his lily pad is pulled downward by gravity and lands on another lily pad instead of continuing on in a straight line.

19. Newton's first Law
Principle of Inertia

20. Which Law?
After you start up your motorcycle, as you give it more gas, it goes faster.

21. Newton's second Law
Accelerated Motion

22. A pitched baseball goes faster than one that is gently thrown.
Which Law?
A pitched baseball goes faster than one that is gently thrown.

23. Newton's second Law
Accelerated Motion

24. When you paddle a canoe, the canoe goes forward.
Which Law?
When you paddle a canoe, the canoe goes forward.

25. Newton's third Law
Action-Reaction

26. Which Law?
As an ice skater pushes harder with his leg muscles, he begins to move faster.

27. Newton's second Law
Accelerated Motion

28. Which Law?
A little girl who has been pulling a sled behind her in the snow is crying because
When she stopped to tie her hat on, the sled kept moving and hit her in the back
of her legs.

29. Newton's first Law
Principle of Inertia

30. All about Forces! A. B. C. D.