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Intro to Newton’s Laws

Sir Isaac Newton… What was he thinking???

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Bowling Ball Races

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Bowling Ball Races

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Bowling Ball Races

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What makes something *move?

*”move” is NOT a great “physics word”... Us Physics Folk need to be more precise…

Details coming…

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Things that make something move:

What’s the generic definition?

FORCES

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Specific Names of Types of Forces

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Types of motion - “States of Motion

What states do the pictures represent?

accelerating?

Static equilibrium?

Dynamic equilibrium?

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More types of motion

accelerating?

Static equilibrium?

Dynamic equilibrium?

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Don’t forget this one!

accelerating?

Static equilibrium?

Dynamic equilibrium?

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States of Motion Summary

  1. Equilibrium = Balanced = NOT Accelerating
    1. Static equilibrium: Not accelerating & Not moving

    • Dynamic equilibrium: Moving but NOT accelerating

  • Unbalanced = Accelerating
    • Speeding up

    • Slowing down

    • Turning

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Newton’s First Law of Motion, using precise physics vocabulary...

  1. Common Language:
    1. An object at rest stays at rest (static)
    2. An object in motion stays in motion (dynamic)
    3. Unless acted upon by an “outside Force”.

  • Precise Physics Language: An object will maintain constant velocity unless acted upon by an “unbalanced” Net Force.

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Play Asteroids!!!

Compare these two games and explain

Newton’s LAWS of MOTION!!!

  1. OP2.1 PQM SPACESHIP LAWS of MOTION:
    1. CONTRAST Asteroids#1 & Asteroids#2
      1. How does the rocket speed up?
      2. How does the rocket slow down?
      3. How does the rocket turn?
      4. What happens when the rocket is moving?
      5. What happens when the rocket is stopped?

Score 5000 in each game?

Which one is more difficult?

Which is a more “accurate depiction” of Newton’s Laws in space???

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OP2.1 PQM SPACESHIP LAWS of MOTION:

CONTRAST

Asteroids#1 & Asteroids#2 (which one is “more correct to Newton’s Laws?)

  • How does the rocket speed up?
  • How does the rocket slow down?
  • How does the rocket turn?
  • What happens when the rocket is moving?
  • What happens when the rocket is stopped?

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Part 2

Free Body Diagrams (FBDs)

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Forces, Vectors & Motion

What will happen in the following four situations?

Remember this is EXACTLY like the 2.3 Warm-up Question???

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Do you know Newton’s

“Laws of Motion”?

1.

2.

3.

What’s the well-known definition/statement about Newton’s First Law?

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Newton’s First Law of Motion, using precise physics vocabulary...

  • Common Language:
    • An object at rest stays at rest (static)
    • An object in motion stays in motion (dynamic)
    • Unless acted upon by an “outside Force”.

  • Precise Physics Language: An object will maintain constant velocity unless acted upon by an “unbalanced” Net Force.

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Free Body Diagrams

What will happen in the following four situations?

  • Which ones could be Static or Dynamic Equilibrium?
  • Which ones could be accelerating?
  • Can we mathematically solve for acceleration here? Why or why not???
    • See Part 3 of this presentation for answers to that...

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Free Body Diagrams

Or

FBD’s

1

4

2

5

6

GIVE/TAKE THESE NOTES BY HAND...

7

8

9

3

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Free Body Diagram Interactives

FBD’s

ThePhysicsClassroom.com

SUBMIT A SCREENSHOT OF A CORRECT ANSWER ON WIZARD LEVEL TO SCHOOLOGY FOR CREDIT!!!!

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Part 3

Newton’s 2nd Law

F ~ a

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What else???

If a push or pull affects how something moves… Is there anything else that affects it??

need a hint???

F ~ a

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That Brings us to Newton’s Second Law

2.

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TED video on Newton’s Laws

First two minutes covers through Newton’s First and Second Laws

0:00-1:56

Third Law follows

1:57-3:32

but we’ll cover that in more detail later!

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Free Body Diagrams

What if the mass of each is 5kg?

What can we say about the motion now?

PROVE you can do this on Sparky Quiz 2.2 Newton’s Second Law!!!

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Part 4

Newton’s 2nd Law

And “Mr. Bean’s Wild Ride” wkst

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Consider the following situations...

Unbalanced!

Accelerating

NSL

Newton’s 2nd Law!!!

a = Fnet/m

Balanced!

NOT

Accelerating

NFL

Newton’s 1st Law

An object maintains constant velocity unless acted upon by an unbalanced Net Force!!!

Speeding up...

Slowing Down...

Constant...

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Newton’s 2nd Law

And “Mr. Bean’s Wild Ride” wkst

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STOP: Next Section Under Construction!

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Free Body Diagram Worksheet

Complete the following worksheet

  • 𝞢𝑭𝒙 & 𝞢𝑭𝐲 represent the sum (𝞢) of the forces in the horizontal (𝒙) and vertical (𝐲) directions.
  • a𝒙 & a𝐲 represent the acceleration in the horizontal (𝒙) and vertical (𝐲) directions.

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In Class Scenarios: #1

Get out 2 peices of paper

Split each page in half, top and bottom

each scenario (6) will be represented in top or bottom half

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#2

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#3

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#4

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#5

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#6

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Free Body Diagrams

Constructing FBD’s (Note: Might be harder than they look!?)

(You’ll have to be able to use the names of Forces learned earlier in this presentation)

physicsclassroom.com/Free-Body-Diagram-Interactive

Try a few together as a class, and the rest on your phone but you can ask your neighbor for help if you need it...

Check back with your teacher when you get stuck and go over results or ask questions at the end!

(HINT: We’re on Earth which has gravity everywhere!!!)

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Questions from FBD Interactive

Free Body Diagrams The Free Body Diagrams Interactive consists of 12 verbal descriptions for which free-body diagrams must be correctly drawn. The 12 descriptions are shown below. Verbal Description

1. A rightward force is applied to a crate to push it across the floor at a constant speed. Ignore air resistance.

2. A rightward force is applied to a dresser to accelerate it to the right across the bedroom floor. Ignore air resistance. 3. A rightward-moving car is skidding to a stop across a level roadway with locked wheels. Ignore air resistance.

4. A football is moving upward and rightward towards the peak of its trajectory. Ignore air resistance.

5. The cabin of a small freight elevator is secured to a motor by a cable and is moving upward with a constant speed. There is no contact between the cabin and the elevator shaft. Ignore air resistance.

6. A downward-moving skydiver is falling with a constant speed.

7. A hockey puck glides to the right across the ice at a constant speed. Ignore air resistance.

8. A sledder has reached the bottom of a hill and is coasting to the right while slowing down along the loosely-packed snow. Ignore air resistance.

9. A football, originally kicked at an 40-degree angle to the horizontal, is at the peak of its trajectory. Ignore air resistance.

10. A downward-moving skydiver who has just opened the parachute is slowing down. (Diagram the forces on the skydiver/parachute combination.)

11. The cabin of a small freight elevator is secured to a motor by a cable and is moving upward while slowing down. There is no contact between the cabin and the elevator shaft. Ignore air resistance.

12. A softball player does a head-first dive and is sliding to the right across the infield dirt. Ignore air resistance.

answers on next slide...

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Answers to FBD Interactive

Careful cuz they pop up in different order each time you restart the interactive???