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Chapter 13 Motion

Chapter 13 Motion. DO NOW. What kinds of things have motion? What do you know about motion?? How can you describe motion? What are some motions you went through today?. Sitting at your desk, are you moving in relation to your chair? Are you moving in relation to anything???.

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Chapter 13 Motion

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  1. Chapter 13Motion

  2. DO NOW • What kinds of things have motion? • What do you know about motion?? • How can you describe motion? • What are some motions you went through today?

  3. Sitting at your desk, are you moving in relation to your chair? • Are you moving in relation to anything???

  4. Types of Motion

  5. Rate • When do you see motion at different rates?

  6. When do you see constant motion?

  7. When do you see variable motion?

  8. Motion in many directions

  9. Periodic Motion

  10. Circular Motion

  11. Vibrating Motion

  12. DO NOW:

  13. DO NOW • What is a force? • When have you heard the word “force” used before? • What are some qualities of forces? (ways you could describe forces)

  14. Characteristics of Forces

  15. Important: • Objects do not change their motion unless acted upon by an outside force!

  16. GRAVITY • PREDICT IN YOUR NOTEBOOKS: • When you drop them at the same time, what will hit the ground first: • A pencil , book, or ruler? • Which will hit last??

  17. GRAVITY • You already know: • Earth’s gravity pulls objects toward its center without ever touching them. • It’s why satellites stay in orbit, why pendulums swing, and why apples fall off trees to the ground.

  18. Gravity • Maybe you know: • Gravity is different on different planets. • Your weight is a measure of the pull of gravity between you and the Earth. • It depends on your mass and the earth’s mass. • It also depends on how far above the earth you are.

  19. Gravity • You probably DON’T know: • Every object in the universe exerts a gravitational pull on every other object, but only the gravity of a large object (like earth) is strong enough to be felt.

  20. DO NOW • Take this out from yesterday and continue working if you need to. • What are places you see speed in everyday life? • What do you know about speed?

  21. Point of Reference • Motion is measured in relationship with some location called a point of reference. • Imagine riding on a train. You are not changing position relative to the seat you are in, but you are definitely changing position in relation to the ground or the towns you are passing.

  22. What if you were walking toward the rear of a train while the train is moving very slowly forward?

  23. Imagine you are in Illinois. There is a tornado moving at a speed of 50 mph in neighboring Indiana. Is this enough information to know if you need to evacuate your town?

  24. NO! • You would need to know not only the speed of the tornado, but also the DIRECTION the tornado is moving in!!!

  25. Speed + Direction = velocity! • When you know the speed AND the direction of an object’s motion, then you know the object’s VELOCITY!

  26. Speed or Velocity? Speed • 19.3 miles/hour • 289 mph • 3 meters/sec S • 1.9 cm/s W • 2,000 mi/h Speed velocity velocity speed

  27. Common Forces • 1. Gravity • 2. Magnetism • 3. Electricity • 4. Friction

  28. Magnetism • Magnetism is a force that pushes and pulls on objects. • Magnets have 2 poles – N and S • Magnets exert magnetic force on objects made of iron and certain other elements • Opposites attracts • Likes repel

  29. Electricity • Objects get electrically charged when they gain or lose ELECTRONS. • Imagine an atom has 3 protons and 3 electrons. What is the OVERALL charge on the atom? • Then, it gains 2 electrons. Now, what is the overall charge on the atom?

  30. Imagine you have an atom with 3 protons and 3 electrons and it loses 2 of its electrons. Now what charge does it have???

  31. Friction • Force that results when 2 materials rub against each other • It goes AGAINST motion • It slows it OR keeps it from starting • Depends on 2 things: • 1. texture of surface • 2. how hard they press against each other

  32. Types of Friction • Air friction • Water / fluid friction • Sliding friction • Static friction (objects that are not moving)

  33. What are sports where friction is helpful? • Soccer – cleats

  34. What are sports where athletes attempt to reduce friction? • Swimming – suits, caps, body position to avoid friction • Ice skating

  35. Gravity, Electricity, and Magnetism • All can act at a distance and do not require touching. BUT they are stronger when the objects are closer. • Magnetism and Electricity can be blocked, but gravity cannot.

  36. WORK – which of these scenarios is the most work done and why? • 1. holding a 20 pound backpack on your back for ten minutes • 2. lifting a 2 pound backpack from the floor to the kitchen counter • 3. running on a treadmill for 2 miles

  37. WORK AND POWER • Work, work, work. You might head off to your job one day, sit at a computer, and type away at the keys. That's all we do here. Is that work? • To a physicist, only parts of it are. • Work is done when a force that is applied to an objectmovesthat object in the same direction of the force.

  38. The work is calculated by multiplying the force by the amount of movement of an object • (W = F x d). • Kayla exerts a force of 10 Newtons on her science book. She moves her book 3 meters. How much work did she do? W = F x D W = 10 Newtons x 3 meters W = 10 N x 3 m W = 30 N*m Kayla does 30 Nm of work.

  39. A “Newton-meter” is quite a mouthful! • Thus, scientists came up with a much easier term to describe Newton-meters. • 1 Newton-meter = 1 JOULE!

  40. SOOO…. • Work is measured in newton-meters, also known as JOULES!

  41. WORK , or NO WORK? • Sitting and looking at a computer screen * No work!

  42. Tapping on the keyboard and making the keys move • Yes work! • You are applying a force and making the keys move!

  43. Driving to your job is not work because you just sit, but the energy your car engine uses to move the car does work.

  44. Imagine that you are holding a brick above the ground. Your arm is straight out in front of you and it's pretty tough to hold. Slowly, your arm gets tired, the brick feels heavier and heavier, and you finally have to stop to let your arm rest. Even though you put forth a lot of effort to hold the brick up, did you do any work on the brick? Nope. The brick didn't move. No work was done if no movement happened. If you lifted the brick again after your arm had rested, that would be work.

  45. DO NOW • Morgan walks up the stairs, and it takes him 20 seconds. Her sister Lexi runs up the stairs and arrives at the top in only 4 seconds. • Who does more work? Why?

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