1. The Third Law of Motion

2. 1. Newton’s Third Law of Motion –

3. 1. Newton’s Third Law of Motion –
To every action force there is an equal and opposite reaction force

4. 1. Newton’s Third Law of Motion –
To every action force there is an equal and opposite reaction force
When one object exerts a force on a second object, the second one exerts a force on the first that is equal in size and opposite in direction

5. 1. Newton’s Third Law of Motion –
To every action force there is an equal and opposite reaction force
When one object exerts a force on a second object, the second one exerts a force on the first that is equal in size and opposite in direction
Forces are equal, but they are NOT balanced

6. 1. Newton’s Third Law of Motion –
To every action force there is an equal and opposite reaction force
When one object exerts a force on a second object, the second one exerts a force on the first that is equal in size and opposite in direction
Forces are equal, but they are NOT balanced
Examples: trampoline, swimmer, rocket propulsion

7. Newton’s Laws
1. First Law – (inertia) – an object moving at a constant velocity keeps moving at that velocity unless a net force acts on it; an object at rest stays at rest unless a net force acts on it

8. Newton’s Laws
2. Second Law – (f = m x a) – a net force acting on an object causes the object to accelerate in the direction of the net force

9. Newton’s Laws 3. Third Law – (action-reaction pairs)
To every action force there is an equal and opposite reaction force

10. 2. Gravity and the planets –

11. 2. Gravity and the planets –
The orbit of every planet is affected by the gravitational pulls from all the other planets

12. 3. Momentum–

13. 3. Momentum–
A property that a moving object has because of its mass and velocity (speed&direction)

14. 3. Momentum–
A property that a moving object has because of its mass and velocity (speed&direction)
Momentum is related to how much force is needed to change the motion of a moving object

15. 3. Momentum–
A property that a moving object has because of its mass and velocity (speed & direction)
Momentum is related to how much force is needed to change the motion of a moving object
Increasing either the speed or the mass of an object makes it harder to stop

17. 4. Calculating Momentum –

18. 4. Calculating Momentum –
momentum = p

19. 4. Calculating Momentum –
momentum = p
momentum = mass x velocity

20. 4. Calculating Momentum –
momentum = p
momentum = mass x velocity
p = m x v

21. 5. Rewrite Newton’s 2nd Law –

22. 5. Rewrite Newton’s 2nd Law –
Recall, a=(vf-vi)/time

23. 5. Rewrite Newton’s 2nd Law –
Recall, a=(vf-vi)/time
Recall, f = m x a

24. 5. Rewrite Newton’s 2nd Law –
Recall, a=(vf-vi)/time
Recall, f = m x a
Combine these relationships -

25. 5. Rewrite Newton’s 2nd Law –
Recall, a=(vf-vi)/time
Recall, f = m x a
Combine these relationship -
Net force = (change in momentum)/time

26. 5. Rewrite Newton’s 2nd Law –
Recall, a=(vf-vi)/time
Recall, f = m x a
Combine these relationships -
Net force = (change in momentum)/time
F = (mvf - mvi) / time

27. 5. Rewrite Newton’s 2nd Law –
Recall, a=(vf-vi)/time
Recall, f = m x a
Combine these relationships -
Net force = (change in momentum)/time
F = (mvf - mvi) / time
(mvf=final momentum, mvi=initial momentum)

28. 6. Law of Conservation of Momentum –

29. 6. Law of Conservation of Momentum –
Momentum of an object doesn’t change unless it mass, velocity, or both change

30. 6. Law of Conservation of Momentum –
Momentum of an object doesn’t change unless it mass, velocity, or both change
HOWEVER, momentum can be transferred from one object to another

31. 6. Law of Conservation of Momentum –
Momentum of an object doesn’t change unless it mass, velocity, or both change
HOWEVER, momentum can be transferred from one object to another
The Law states that if a group of objects exerts forces only on each other, their total momentum doesn’t change