1. You need: Clean paper / pencil Warm Up: State the law of conservation of energy – and give ONE sentence to explain it. I CAN: define the first law of motion (it’s characteristics and applications)
Nov.21, 2017

2. Making a foldable: Newton’s Laws of
Making a foldable: Newton’s Laws of Motion On the inside, include the following info for each law: 1) What does the law say? 2) What’s an example of a situation that shows the law in action. 3) Draw a picture that shows the law in action *Use the textbooks:
NEWTON’S
LAWS
Newton’s First Law of Motion
Newton’s Second Law of Motion
Newton’s Third Law of Motion

3. THE LAW OF
Newton’s 1st Law
INERTIA

4. Newton’s 1st Law of Motion
After the ball is kicked, what forces are acting on it while it rolls?
What if we could remove those forces? What would happen then if we kicked the ball?
GRAVITY
Friction

5. Newton’s 1st Law of Motion
Newton’s 1st law of motion states:
An object at rest will remain at rest,
-and-
an object moving at a constant velocity will continue moving at a constant velocity,
-UNLESS-
it is acted upon by an unbalanced force.

6. Newton’s 1st Law of Motion
BASICALLY…
Objects resist any change to their motion!
This resistance is called INERTIA.
Which one would be easier to push?
or…
That’s because larger objects have more inertia (more resistance to a change in their motion)!

7. Newton’s 1st Law of Motion
Unfortunately, your bed really doesn’t make itself…
And dirty clothes won’t pick themselves up off the floor!
That’s because things at rest will stay at rest until an unbalanced force (like your arms lifting the sheets) acts on them.
Make your bed!
Do the laundry!

8. Newton’s 1st Law of Motion
What would happen to the things inside the car if the car hit a wall?
That’s because things moving at a constant velocity will stay at a constant velocity unless acted upon by an unbalanced force.
The car was acted upon by an outside force – the force of the wall hitting the car.
The person inside the car wasn’t hit by the force of the wall, so he kept moving at the same speed and in the same direction.
Inside a moving vehicle, everything is moving at the same velocity – your body, the objects in the car, and the car itself.

9. Newton’s 1st Law of Motion
Explain this animation:
The truck is stopped by the force of the impact with the car, but the ladder continues to move at its original speed and in its original direction because of inertia.

10. Newton’s Laws of Motion Foldable 1) Label your foldable like the one shown on the right. 2) Cut along the 2 dotted lines to make flaps. 3) On the inside, write down what the law states. 4) Write down an example of a situation that shows the law in action.
NEWTON’S
LAWS
Newton’s First Law of Motion
Newton’s Second Law of Motion
Newton’s Third Law of Motion

11. THE LAW OF
Newton’s 2nd Law
Acceleration

12. Newton’s 2nd Law of Motion
Newton’s 2nd law of motion describes how UNBALANCED FORCES and MASS affect the ACCELERATION of an object.

13. So, how do unbalanced forces affect an object’s motion?
How does a batter’s swing affect the acceleration of a baseball?
Homerun Hit
Sacrifice Bunt

14. So, how do unbalanced forces affect an object’s motion?
The harder you hit, the faster it goes!
The greater the force, the greater the acceleration…
Homerun Hit
Sacrifice Bunt

15. So, how does mass affect an object’s motion?
Which shopping cart would move faster with a single push?
Empty Cart
Full Cart

16. So, how does mass affect an object’s motion?
The fuller the cart, the slower it goes!
The more mass, the less acceleration…
Empty Cart
Full Cart

17. Newton’s 2nd Law of Motion
It states:
ACCELERATION depends on the object’s MASS, and the net FORCE acting on the object.
We can also write it mathematically:
Force = Mass x Acceleration

18. Newton’s 2nd Law Force = Mass x Acceleration M F A
If you want less acceleration with the same force, you must increase the mass.
If you lower the mass but keep force the same, acceleration will increase. M F A
If you raise the mass but keep force the same, acceleration will decrease.
If you want more acceleration with the same force, you must decrease the mass.

19. Newton’s 2nd Law Force = Mass x Acceleration
If you want less acceleration with the same mass, you must decrease the force.
If you want more acceleration with the same mass, you must increase the force.

20. Newton’s 2nd Law Force = Mass x Acceleration
If you lower the mass but want the same acceleration, you must decrease the force.
If you raise the mass but want the same acceleration, you must increase the force.

21. Newton’s 2nd Law of Motion
Force = Mass x Acceleration
Mr. Sawyer’s car ran out of gas. How much force does Mr. Sawyer need to push his 750kg car at an acceleration of 1 m/s2?
F = m x a
F = 750 kg x 1 m/s2
F = 750 N right
750 kg
1 m/s2

22. Try one on your own…
Ms. Litwak’s van runs out of gas. How much force does she need to push the 2000kg van at an acceleration of 0.5 m/s2?
0.5 m/s2
F = m x a
F = 2000 kg x 0.5 m/s2
F = 1000 N right

23. Newton’s 2nd Law of Motion
Speed, Distance & Time
We can also write the formula like this:
Acceleration = Force
Mass
Mass = Force
Acceleration
Force = Mass x Acceleration m F a

24. Newton’s 2nd Law of Motion
Find the golf ball’s acceleration.
The putter hits the 0.05 kg golfball with a force of 1 N.
The driver hits the 0.05 kg golfball with a force of 8 N.

25. Newton’s 2nd Law of Motion
Use Newton’s 2nd law of motion to explain in words the difference in the motion of the golf balls.

26. Newton’s Laws of Motion Foldable 1) Label your foldable like the one shown on the right. 2) Cut along the 2 dotted lines to make flaps. 3) On the inside, write down what the law states. 4) Write down an example of a situation that shows the law in action.
NEWTON’S
LAWS
Newton’s First Law of Motion
Newton’s Second Law of Motion
Newton’s Third Law of Motion

27. THE LAW OF
Newton’s 3rd Law
Interaction

28. Which forces are acting to get this guy up in the air?
His feet push DOWN on the ground.
But wait… His downward push can’t be causing his upward motion.

29. Which forces are acting to get this guy up in the air?
His feet push DOWN on the ground.
The ground pushes UP on the man.
There must be a force pushing UP!
The force of the ground pushes him UP!

30. Newton’s 3rd Law of Motion
Newton’s 3rd law says that: For every action force, there is an equal and opposite reaction force.
ALL forces act in PAIRS!
Action Force: Man’s feet push DOWN on the ground.
Reaction Force: Ground pushes UP on the man.

31. Let’s Demonstrate…
Stand up and face a partner with your palms touching.
Push on your partners hands. Don’t move your feet. The first partner to step back loses…
How can Newton’s third law explain what happens?

32. Newton’s 3rd Law of Motion
Explain this animation using Newton’s third law.

33. Newton’s 3rd Law of Motion
The man’s foot exerts a backward push on the boat (action force), while the boat exerts a forward push on the man (reaction force).
A PAIR OF FORCES:
EQUAL FORCES, BUT IN OPPOSITE DIRECTIONS

34. Let’s Demonstrate…
Two people (the same size) in rolling chairs face each other with their feet touching.
Only 1 student pushes. What will happen?
How can Newton’s third law explain what happens?

35. Identify the force pairs in each situation
A person fires a rifle.
Action Force – gun pushes the bullet out at high speed.
Reaction Force – the bullet pushes back on the gun (recoil).

36. Identify the force pairs in each situation
A space shuttle lifts off.
Action Force – engine pushes gases down & out.
Reaction Force – the gases push the rocket up.
*This upward force must be stronger than gravity pulling down on the rocket!

37. Identify the force pairs in each situation
A person stands still.
Action Force – gravity pulls the person down to the floor.
Reaction Force – the floor pushes up on the person.
*You don’t need MOTION for force pairs. They are everywhere!

38. If forces are equal and in opposite directions, why don’t they cancel out (and balance)?
Forces only cancel if they act on the same object. (Think about a tug of war – all forces act on the rope).
These forces are acting on different objects!
These forces are acting on different objects!
Action Force – Rocket engine pushing on gases.
Reaction Force – Gases push on the rocket.

39. Think about it . . . Why does it hurt so much when you stub your toe?
When your toe exerts a force on a table, the table exerts an equal force back on your toe.
The harder you hit your toe against it, the more force the the table exerts back on your toe (and the more your toe hurts).

40. What is Momentum? Momentum is a measure of how much motion object has.
It is affected by mass and velocity. The heavier an object is, the more momentum it has.
It’s easier to stop soccer ball coming towards you at 20 m/s than a car coming at 20 m/s.
It’s easier to stop car travelling at 1 km/h than a car travelling 60 km/h!

41. Conservation of Momentum
When objects collide, their total momentum is conserved (stays the same), unless outside forces act.
The total amount of motion coming into a collision will also come out of the collision.

42. Place 4 coins in a row, touching each other.
Place the 5th coin about 2 inches away from the end of the row, keeping it in line.
Lightly flick your finger forward, propelling the single coin against the others.
What do you observe?
Try it again, flicking 2 coins into a row of 3 coins. What do you observe?

43. Momentum = mass x velocity
Momentum can be calculated using this formula:
Momentum = mass x velocity
A golf ball with a mass of 0.05 kg travels at 16 m/s.
A baseball with a mass of 0.15 kg travels at 7 m/s.
Which ball has the greater momentum?
Golf ball’s momentum = 0.05 kg x 16 m/s
Baseball’s momentum = 0.15 kg x 7 m/s
= 0.8 kg m/s
= 1.05 kg m/s