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Come on People This is not rocket science

Come on People This is not rocket science. Oh, Wait. Yes it is!. Newtons First Law. Chapter 6 Section 2 Saturday, October 11, 2014. Force. An objects movement changes in response to a force A force is a push or a pull Can be a contact force A push or a pull Can be a long range force

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Come on People This is not rocket science

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  1. Come on PeopleThis is not rocket science

  2. Oh, Wait Yes it is!

  3. Newtons First Law Chapter 6 Section 2 Saturday, October 11, 2014

  4. Force • An objects movement changes in response to a force • A force is a push or a pull • Can be a contact force • A push or a pull • Can be a long range force • Gravity • Magnetism

  5. Newton's First Law of Motion • An object at rest stays at rest unless acted on by an outside force • An object in motion stays in motion unless acted on by an outside force

  6. Force • SI unit for force is the Newton (N) • About the force needed to lift 4 ounces of water

  7. Newtons First Law • An object in motion tends to stay in motion unless acted on by an outside force. • An object at rest tends to stay at rest unless acted on by an outside force. • Also known as inertia

  8. Inertia and Mass • The more mass an object has the more inertia it has • The more inertia an object has, the harder it is to change its motion. • So lets look at Football Physics

  9. Which would be better as a football lineman? Why?

  10. Adding Forces • The motion of an object changes only if a force is acting on it • More than one force can act on an object • If forces act in opposite directions with equal force, no motion happens • Balanced Forces

  11. Adding Forces • If one force is greater than the other the object will move in the direction of the larger force • Motion only changes if forces are unbalanced • Motion changes in the direction of the greater force

  12. Newton’s Second Law Chapter 6 Section 3

  13. The Second Law of Motion • Used to predict Motion • An object acted on by an unbalanced force will accelerate in the direction of the force • This law is actually a formula

  14. The Second Law of Motion Acceleration = Force / Mass Or Force = Mass x Acceleration

  15. Or • F=MA

  16. Force Measured • The SI Unit for Force is the Newton • One Newton of Force will cause 1 kg of Mass to Accelerate at 1M/S2 • So 1N = 1M/S2/kg

  17. Sample Problem • A child has a mass of 71kg • Her Bike has a mass of 9 kg • They accelerated at a rate of 3.2M/S2 • How much force was applied? • Well, force equals mass times acceleration • So F = 80kg x 3.2M/S2 = 256 kg/M/S2 • Or 256N

  18. Force of Gravity • Gravity is a force • The force of Earth’s gravity causes all objects to accelerate at the same rate when falling • The rate is 9.8M/S2

  19. NASCAR Physics “Physics is good stuff”

  20. What in the wide, wide world of sports has this stuff got to do with racing???

  21. Well….. • In scientific terms acceleration and mass are inversely related. • If the force is the same (Like say from the engine) • The more mass you have, the less acceleration you get • Or the heavier the car, the slower the acceleration given the same amount of horsepower

  22. So, which would be better as a racecar driver? Why?

  23. That was heavy! • Speaking of heavy • That leads us to weight • So wait around for the next fascinating fact

  24. The Bigger They Are The Harder They Fall (But Not Faster) • Weight = Mass X Acceleration due to Gravity. • So… • If your mass is 60kg • 60kg x 9.8 M/S2 = 588N • In science, weight is expressed as Newtons

  25. Silly Scientists!

  26. Say What??? • Because weight is the force caused by gravity acting on mass. • The same force is acting on you whether you are falling or standing on the ground.

  27. Mass and Weight • In common language mass and weight are spoken of as the same thing. • In zero gravity you have no weight (that’s why we call it weightless) • But you have the same mass. • On the moon, you would have about 1/6th of you earth weight but the same mass

  28. A balance is used for measuring mass because a balance compares an object's mass to a set of standard masses

  29. A spring scale is used for measuring weight because a spring scale measures the forceof gravity pulling objects downward.

  30. 1kg of bananas weighs 9.8N on Earth. 1 kg of bananas have a mass of 1.0 kg on Earth.

  31. 1kg of bananas weighs 3.7N on Mars. 1 kg of bananas have a mass of 1.0kg on Mars (even if they're Martian bananas)

  32. Football Physics • Would the advantage be the same on the moon? • Yes, the mass is the same, the force is caused by mass not weight.

  33. Friction • A force that resists motion • But is essential to our lives • Could you get here without friction • No • Why?

  34. Without Friction… Moving is a bear

  35. Three Types of Friction

  36. Static Friction • Why does the food not slide off the tray when the waiter starts or stops? • Static friction resists movement relative to the tray.

  37. Sliding Friction Will the glass make it? What will slow it down? What will make it slide better?

  38. Rolling Friction

  39. Air Resistance

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