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Warm-up 2/16/11

Warm-up 2/16/11. Review: Tell me anything you can think of about Newton’s Laws (even if it’s the obvious). Review: List any forces acting on you now as you sit in your desk and if you were to get up and give me a dollar.

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Warm-up 2/16/11

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  1. Warm-up 2/16/11 • Review: Tell me anything you can think of about Newton’s Laws (even if it’s the obvious). • Review: List any forces acting on you now as you sit in your desk and if you were to get up and give me a dollar. • Teach the Teacher: Who is the most inspiring person in your life (besides me)?

  2. Newton’s Laws of Motion They are hard to break

  3. NEWTON • If I have seen farther than other men, it is because I have stood on the shoulders of giants." -Isaac Newton • When Newton made that famous statement, he was referring to such giants as Tycho Brahe, Johannes Kepler, and, most specifically, Galileo Galilei

  4. History behind the First Law of Motion • Prior to Galileo and Newton's work on motion, it was believed that the natural tendency of objects was to come to rest. • Sooner or later, moving objects would stop moving. • Meaning that some force was necessary to keep an object in motion. • Aristotle and Ptolemy. • Galileo boldly asserted the exact opposite. • He reasoned that moving objects eventually stopped moving due to a force called friction. • Galileo's Experiment • Galileo developed the concept of inertia.

  5. What Galileo did: • Galileo's Experiment

  6. The ball would roll forever…..Like in space

  7. Newton’s First Law of Motion - INERTIA • Objects at rest stay at rest unless acted on by another force. • Objects in motion stay in motion unless acted on by another force • There is a natural tendency for objects to resist changes in their state of motion.

  8. Inertia • INERTIA – The resistance of an object to a change in its state of motion. • The more mass an object has, the greater inertia.

  9. Shooting Objects at RestThe object’s inertia causes it to remain still even when a bullet passes through it.

  10. FORCE • is a push or a pull • can give energy to an object causing the object to: • start moving, • stop moving, • change its motion.

  11. Force, Mass & Acceleration • For any object, the greater the force applied to it, the greater its acceleration. • The acceleration of an object depends on its mass as well. • Force, mass, and acceleration are connected.

  12. Balanced vs. Unbalanced • Balanced forces • They are equal in size and opposite in direction • Do NOT cause a change in motion. • Result in a zero net force • Net force is the result of all the forces acting on the object • Unbalanced forces • They are unequal in size and or in the same direction • Cause a change in motion

  13. Units • The SI unit for mass =kilogram (kg) • The unit for acceleration = meters per second squared (m/s2) • So the unit for force = kg x m/s2 • The kg x m/s2 is called the newton (N)

  14. Tugboat Problems • Two tugboats are moving a barge. Tugboat A exerts a force of 3000 Newtons on the barge. Tugboat B exerts a force of 5000 Newtons in the same direction. What is the combined force on the barge? Draw arrows showing the individual and combined forces of the tugboats.

  15. Tug Boat Questions • Now suppose that Tugboat C exerts a force of 2000 Newtons on the barge and Tugboat D exerts a force of 4000 Newtons in the opposite direction. What is the combined force on the barge? Draw arrows showing the individual and combined forces of the tugboats.

  16. Tugboat questions • Could there ever be a case when Tugboat E and Tugboat F are both exerting a force on the barge but the barge doesn't move? Draw arrows showing the individual and combined forces in such a situation.

  17. Physics To Win It Challenge • http://www.nbc.com/minute-to-win-it/how-to/keep-the-change/ • The Challenge: pull an index card from under a penny and have it land in the cup 3 times within a minute. • On index card explain how inertia is effecting the card and penny

  18. Warm-up 2/18/11 • Review: Give as many examples of a force as you can think of ( ex: pulling a puppy across the room) • Teach the Teacher: What is your favorite salad dressing?

  19. Flash Card • On the front write: • Inertia • On the back write: • The resistance of an object to a change in its state of motion.

  20. Flash Card • On the front write: • Newton’s First Law • On the back write: • Objects at rest stay at rest • Objects in motion stay in motion…. unless acted on by another force

  21. Flash Card • On the Front write: • Force • On the back write: • is a push or a pull • can give energy to an object causing motion

  22. Newton’s Second Law • The acceleration of an object is dependent upon the force acting upon the object and the mass of the object.

  23. Actions into Equations • Newton’s Second Law can be written as the equation: F = m x a    • F = force (N)  Newton is the SI Unit of force • m = mass (kg)    N = kg m / s2 • a = acceleration (m/s/s)

  24. Solving the 2nd Law Force Divide Acceleration Mass Multiply Cover up the section you are solving for and the triangle will tell you how to manipulate the problem.

  25. Friction A force that opposes motion between two surfaces that are touching each other The amount of friction is dependant upon Surfaces Force pressing the surfaces together

  26. Types of Friction • Static Friction • Friction between two objects that are NOT moving. • Sliding Friction • Friction between two surfaces moving past each other. • Rolling Friction • Friction between a rolling object & the surface it is rolling on. • Fluid Friction • Friction between an object and a gas or liquid • Encarta Friction Animation

  27. Who am I? • Acceleration • Speed • Inertia • Force • Velocity • Friction • Gravity • Newton

  28. Warm-UP 2/23/11 • Review: In your notes put a star by the two of newtons laws that we have covered so far. • Teach the Teacher: What is your favorite cereal?

  29. Flash Card • On the front write: • Balanced forces • On the back write: • No motion, zero net force,

  30. Flash Card • On the front write: • Unbalanced forces • On the back write: • Motion occurs, either add or subtract to get net force

  31. Flash Card • On the front write: • Newton’s 2nd law • On the back write: • Acceleration of an object depends on the mass and force • F=ma

  32. Who am I? • Velocity • Speed • Friction • Acceleration • Unbalanced force • Balanced Force • Newton’s Second Law • Force • Newton’s First Law • Inertia

  33. Warm-Up 2/25/11 • Review: Draw the triangles for speed, acceleration, and force • Teach the Teacher: What is your favorite type of activity in this class (notes, labs, whiteboard challenge,ect) What is your least favorite?

  34. Physics To Win It • Hole in One • Challenge: To roll a golf ball off the ramp, off the table, and land in the cup…I have to see it. • Jackpot challenge: To get a golf ball to do the above, bounce once and land in the cup • On an index card calculate the velocity of the ball

  35. Air Resistance • When an object falls, it is pulled downward by gravity. • Air resistance—a force that acts on objects as they fall through the air. • The amount of resistance on an object depends on the speed, size, and shape of the object. • A feather will fall more slowly than an apple

  36. Air Resistance Dependent on… • a variety of factors, most importantly • the speed of the object • Increased speeds = increased air resistance. • the cross-sectional area of the object • Increased cross-sectional area = increased air resistance.

  37. List the examples of friction in this picture

  38. Gravity • Universal law of Gravity • Any two objects will exert an attractive force on each other • The size of the force is dependant on • Mass of both objects • Distance between the objects

  39. Falling Objects on Earth • Near Earth’s surface • Acceleration due to gravity • 9.8 m/s2 or ~ 10 m/s2 • If a bowling ball and a marble are dropped from the same height, which would hit the ground first? Simultaneous drop of two objects with different masses dropping objects on the moon

  40. Weight Force of gravity pulling you toward the earth SI Base Unit = Newtons Weight can change with a change in location. Mass A measure of how much matter any object has You know an object has mass because it has inertia SI Base Unit = Kilograms http://www.exploratorium.edu/ronh/weight/ Weight vs. Mass

  41. Warm-Up 3/1/11 • Review: Draw a picture of an example of friction (use your notes!) • Teach the Teacher: If you could be any animal what would you be? • Learning Target: • Factors that effect air resistance • Difference between weight and mass

  42. Air Resistance Challenge • Put your name on both sheets of paper • One sheet=design a “papercraft” that will have A LOT of air resistance • Other sheet=design a “papercraft” that will have VERY LITTLE air resistance • WHEN DROPPED FROM THE SECOND STORY BALCONY • YOU WILL FAIL IF YOU DON’T PICK IT UP!

  43. Air resistance Challenge Card • On one 3x5 card describe your design for the “papercraft” that had A LOT OF air resistance • And tell me why you think it did. • On the other 3x5 card describe your design for “papercraft” that had VERY LITTLE air resistance • And tell me why you think it did.

  44. Flash Card • On the front write: • Air resistance • On the back write: • A force on objects as they fall through the air.

  45. Flash Card • On the front write: • Gravity • On the back write: • An attractive force between two objects depend on the mass and distance between them

  46. Flash Card • On the front write: • Mass • On the back write: • The amount of matter in an object, doesn’t change

  47. Flash Card • On the front write: • Weight • On the back write: • The force of gravity pulling on you, changes in the universe

  48. Roll Say Flash • Materials: Flash cards, game board, dice, partner • While one person is rolling the dice, another person is flipping over flash cards. And seeing if they can say the word, and putting it in appropriate place on game board • The other person is the judge, until they roll a six then trade • Keep playing until the music stops and the one with the fewest, “got it on the first try” has to move to the next table

  49. Warm-up 3/3/11 • Review: What are newton’s laws that we have looked at so far? USE YOUR NOTES! • Teach the Teacher: What is the best pair of shoes you have ever owned? • Learning Target: Types of Friction

  50. American Indian Physics Contributions Related to Friction • Contribution: canoe, pulleys, ect, • Friction Force Used: sliding or rolling or static ect. • Region or Tribe to Thank: • Other interesting fact: • ADD PICTURE AND SOURCE OF PICTURE!

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