1. Newton's Laws

2. 12/02 Newton’s 1st Law/Inertia
IQ: You have the following 3 forces:
5N, 10N, 15N and a toy car. Using all three forces show:
2 situations where the forces are unbalanced. Show net force and dir. Of motion of the car.
b. 1 situation where the forces are balanced.
Show net force and dir. of motion.

3. 12/14 (p.70) Newton’s 1st law/Inertia
In each of the following situations, determine if the forces are balanced or unbalanced and if the object will be at rest, speeding up, slowing down or going at a constant speed. Copy diagrams.

4. 01/04 Newton’s 1st Law of Motion
Turn in yesterday’s classwork (pink half sheet)
Take out Move that Barge (green half sheet)
Answer #10 (4 diagrams) on pink half sheet.

5. First Law of Motion An object at rest will
remain at rest, and an object in motion will
remain at a constant
velocity (straight line, constant speed) unless acted on by an unbalanced outside force.

6. Also called law of Inertia
Inertia– tendency to keep moving or stay at rest.
A moving object doesn’t want to stop moving
A nonmoving object doesn’t want to start moving
Objects won’t start or stop unless FORCED to
The Seatbelt Law
Crash test dummy

7. 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

8. 1st Law = Inertia
An object’s resistance to ANY change in motion (LAZINESS!!)
Mass is a measure of inertia
> mass = > inertia
< mass = < inertia
**easier to stop a bike
than a car
**easier to move a mouse
than an elephant
First law in NFL

9. Think
A moose starts chasing you in the woods. How should you run so you can outrun him- in a straight line or a zigzag motion? Why?

10. Inertia of Rest

12. Common Example of First Law
People commonly encounter the 1st law while sitting in a fast moving vehicle that comes to a sudden stop.

13. 1st Law
An outside force (the collision) stop the vehicle, but passengers continue to move long after the vehicle is stopped.

14. 1st Law
The passengers were thrown out because their bodies continued to move forward at 60 mph without having an unbalanced force to stop them.

16. Ball on chair or ball on book demo

17. EXAMPLES

18. Question
Why do you think infant car seats are rear facing? (Think about what would happen in a head on collision).

19.            
Newton's Laws of Motion
Newton’s First Law: A body continues at rest or in motion in a straight line unless acted on by some force.  
Q: Why do we not observe this usually?
Q: Can you think of other examples (like the astronaut) of times when we do?

21. What about the ladder on top of the truck?
The ladder is in motion because the truck is in motion.
When the truck stops, the ladder stays in motion because of inertia.
The truck is stopped by the force of the car, but the ladder is not.
What force eventually stops the ladder?
Gravity and friction– the two unbalanced forces that slow down and stop most objects on earth.
Inertia and gravity animation study jams

22. Friction & the 1st Law
A moving object wants to keep moving. The only reason it doesn’t on earth is because of friction—the force that causes objects to slow down or stop.

23. NASA video

24. OQ: (Answer on left hand side page)What would this cat’s motion look like if there was no gravity or friction? Use the terms inertia, velocity, and force in your answer.

25. 12/11 Newton’s 2nd Law
IQ: Complete the following based on Newton’s first law:
A pushed cart will __________ in a _________at a ____________, unless an __________ such as _______acts on it.

26. 01/05 p.74 Newton’s 2nd Law of Motion
Take out pink and green half sheets from yesterday. Tape green half sheet from yesterday here.

27. Second Law
of Motion
F = Ma
a = F/M
M= F/a
Force = mass X acceleration

28. 2nd Law of Motion
Acceleration depends on the mass of the object & the force applied to the object.
To cause a higher acc. you need a bigger force.
To cause the same acc. on a higher mass you need a bigger force
AKA: LAW OF ACCELERATION
VS.

29. Which do you think requires a bigger force. A bullet of mass 0
Which do you think requires a bigger force? A bullet of mass 0.2kg shot from rest to 500 m/s in one second or a bowling ball of mass 10 kg moved from rest to 2 m/s in one second. Explain.

30.             
Newton's Laws of Motion
Newton’s Second Law:  

31. Force = mass X acceleration (F = ma)
INCREASE FORCE = INCREASE ACCELERATION
_____ F = ___A DECREASE FORCE = DECREASE ACCELERATION
___F = ___A
Directly proportional

32. INCREASE MASS = DECREASE ACCELERATION __ M = __ A DECREASE MASS = INCREASE ACCELERATION __ M = __ A Inversely Proportional!

33. What does F = ma say?
F = ma basically means that the force of an object comes from its mass and its acc.
Something very massive (high mass) that’s changing speed very slowly (low acceleration), like a glacier, can still have great force.
Something very small (low mass) that’s changing speed very quickly (high acceleration), like a bullet, can still have a great force. Something very small changing speed very slowly will have a very weak force.

34. 2nd Law
All falling objects have the same acc. (due to gravity, 9.8 m/s2), ignoring air resistance.
That means the one with more mass will have more force when it hits the ground and decelerates.
Which will have more force, the elephant or the hockey puck?
Second law in NFL

35. Weight/Gravity is calculated using the second law
Weight (F)= mass(m) x acc. due to gravity (g)
On Earth g= 9.8 m/s/s, rounded to 10 m/s/s
Unit of weight: N
Unit of mass: kg
Unit of acc: m/s/s

36. If the acc. due to gravity were doubled to 19
If the acc. due to gravity were doubled to 19.6 m/s/s, what would happen to your weight?
Calculate the force needed to accelerate a 5kg mass by 25 m/s/s.

37. 2)If a force of 100 N accelerates an object by 5 m/s/s, what is the object’s mass?

38. 3) How much will an object of mass 3 kg accelerate, given a force of 60 N?

39. NASA videos

41. OQ: Based on Newton’s 2nd law, what are 2 ways to make a bowling ball roll faster and farther?

42. 12/15/16 p. 74 Newton’s 3rd law
IQ: Which of the following is true when you punch a punching bag?
The only force is applied by you to the bag.
The bag applies a small force back on you.
The bag applies an equal force back on you.
The bag applies a bigger force back on you.

43. 01/06/17 Newton’s 3rd Law of Motion
Complete blue half sheet on 2nd Law

44. For every action, there is an equal and opposite reaction. Third Law
of Motion
For every action,
there is an equal
and opposite
reaction.

45. 3rd Law of Motion
Every action force has an equal & opposite reaction force
Action/reaction forces don’t work on same object, so don’t cancel out.
If a/r are =, then net force would be 0 = no motion, or nothing to make something stop!
Example: Walking, we push back on ground, ground pushes us forward.
SWIMMING:
Action force = hand pushing on water
EQUALS
Reaction force = water pushing on hand
Personal Jet pack
Water jet packs

46. 3rd Law Forces come in pairs – action and reaction
If body A exerts a force on body B, the body B exerts an equal and opposite force on body A

47. Equal but Opposite
Action and reaction forces will be equal and opposite, the same force acting on a greater mass results in a smaller acceleration.

48. Newton’s 3rd Law Example

50. Think and Answer
A sumo wrestler pushes another wrestler with a force of 400N. How does the third law apply in this situation?

51. Another Example The engine pushes gases down. The rocket goes up as
the gases push up on it.
Third law NFL
Third law NASA
Simpsons
NASA youtube

52. 3 Laws review Ted-ed (3 min)

53. OQ: Based on the 3rd law, identify the action/reaction forces in the following examples:
Ex. Hitting your knee against the table
Action: knee hitting table, table hitting back knee with same force
a. An egg hitting the ground.
b. Wheels of a moving cart.

54. Crash Course 3 laws

55. Charlie Brown I want a dog for Christmas
Find as many examples of each law as you can.

56. 1/8/15 Balloon Rockets Lab p. 90
IQ: According to Newton's 3rd law, we have to push in one direction to move (or accelerate) in the opposite direction. For ex. We have to push back with our feet to walk forward, and car tires have to push on the road in a certain direction to move or turn in the opposite direction. Keeping this law in mind, decide
If a space ship would be able to accelerate (speed up, slow down, or turn) in space, or would it only be able to go at a constant velocity (same speed and direction).
If it can accelerate, what would the amount of acceleration depend upon? Provide your reasoning.

57. OQ: Based on the results of your investigation, would you like to make any changes to the answer to your IQ. Why or why not?