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MOMENTUM? CHAPTER 7

I’d like some please. Momentum Store. MOMENTUM? CHAPTER 7. You might have heard people gaining momentum. What is it and how do you get it???. Sure Thing. MOMENTUM?. You might have heard people gaining momentum. What is it and how do you get it???. Here you go. Momentum Store.

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MOMENTUM? CHAPTER 7

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  1. I’d like some please Momentum Store MOMENTUM? CHAPTER 7 You might have heard people gaining momentum. What is it and how do you get it??? Sure Thing

  2. MOMENTUM? You might have heard people gaining momentum. What is it and how do you get it??? Here you go Momentum Store

  3. Momentum is basically how hard it is to stop something. What would make a moving object hard to stop? MORE MASS (INERTIA) MORE SPEED An object with a lot of mass moving quickly has a lot of momentum

  4. MOMENTUM The faster you are moving the more momentum you have!!!! When playing red rover, why do you run instead of walk when trying to break the chain

  5. Which person would you rather have on your team? A B The more mass ( for a given speed) the more momentum!!

  6. If they are all running the same speed who has the most momentum?

  7. Momentum = mass x velocity p = m v velocity of object (m/s) momentum of object Kg m mass of object (Kg) s Which are vectors both velocity and momentum are vectors

  8. What would happen to the momentum of a cannonball if: speed doubled & mass is constant a.) NO CHANGE b.) x2 c.) 1/2 d.) x4 e.) 1/4

  9. What would happen to the momentum of a cannonball if: speed is constant mass is cut in half a.) NO CHANGE b.) x2 c.) 1/2 d.) x4 e.) 1/4

  10. What would happen to the momentum of a cannonball if: speed is doubled mass is doubled a.) NO CHANGE b.) x2 c.) 1/2 d.) x4 e.) 1/4

  11. Can a bus and a bug have the same momentum?

  12. Momentum = mass x velocity                  = m v

  13. p = m v What is the momentum of an 10 kg object moving at 20 m/s? How fast is a 40 kg object moving if it has the same momentum?

  14. What is the momentum of a 1200 kg elephant at rest?

  15. What does this vector thingee have to do with it? What would direction mean???? r = m v THE DIRECTION of momentum is just the Direction of velocity!!!!

  16. Positive Negative If a car (mass constant) had momentum vectors changing as follows what does it mean? What about signs?

  17. If a car (mass constant) had momentum vectors changing as follows what does it mean?

  18. If a car (speed constant) had its momentum vector change as below what does it mean?

  19. What is the velocity of 750 kg rhinoceros, if its momentum is -2800 kg m/s?

  20. How do you change the momentum of an object? (like a car at constant mass) p = m v Change the velocity --- Accelerate! How do you accelerate an object? Apply a Force!!

  21. When you step on the gas and apply a force to speed up your car, 2 things determine how much your momentum (speed) changes 1.) How far you push the pedal - Magnitude of force 2.) How long you push the pedal - Duration of force (time)

  22. A force applied for a time is called an: IMPULSE Impulse = F Dt Time force is applied Magnitude and direction of force An impulse changes the momentum of an object. More specifically Impulse = Change in Momentum

  23. An object is accelerated from rest by an impulse. How would the change in momentum of the object compare if: The Force was applied for half the time? The Force is twice as strong over the same time IMPULSE = CHANGE IN MOMENTUM

  24. Dv a = Dt plugging in for “a” The equation relating Impulse and the change in momentum it causes can be derived very easily: First a force must be accelerating a mass: F = m a What is the definition of acceleration?

  25. Impulse = change in momentum F = m Dt Dv Applied force time force is applied & time object accelerates Dv F = m Dt Cross multiplying yields form 1 of the equation

  26. F = m Dt Dv F Dt = D p Form 2 of the equation Dv = v2 - v1 F Dt = m(v2 - v1) F Dt = mv2 - mv1 F Dt = p 2 - p 1

  27. F Dt = D p IMPULSE = change in momentum!!!!

  28. All forces are applied over a time period (An Impulse) Even things that appear to be just for an instant

  29. Impact of a racquetball with a wall. a balloon decelerating due to an impulse

  30. When trying to change the momentum a ball two factors count: 1.) Magnitude of Force - how hard you swing 2.) Duration of Force - Follow through F Dt = Dp IMPULSE = change in momentum

  31. Dp = FDt BOTH HAVE THE SAME CHANGE IN MOMENTUM A speeding car (say 60 mph) can come to a stop two ways Both will have the same Dr and the same impulse Dp = FDt Crashing into a wall Gradually applying brakes

  32. You can stop an object QUICKLY requires a LARGE FORCE FDt

  33. Or you can stop an object gradually with a small force FDt BOTH HAVE THE SAME CHANGE IN MOMENTUM

  34. Why is a falling glass more likely to break when it hits concrete than carpet? Objects that cushion, spread the force out over a longer time

  35. What is the safest way to land from jumping off a roof?

  36. What involves the greatest change in momentum What involves the greatest IMPULSE? What involves the greatest FORCE? Slowing from 60 m/s to rest Quickly or Slowly

  37. The puncher wants to deliver a large force over a short time (reducing the momentum of his fist) The puncher could have gently pushed his opponent for a minute and changed his momentum just as much

  38. Rolling with the punches If time of contact with the punch is doubled, what happens to the force of the punch? The puncher wants to deliver a large force, How could the punchee reduce the force?

  39. Other times you want a large force over a short period

  40. Other examples: Air bags Bungee Jumping Crumple Zones in Cars Egg and bed sheet demo

  41. What is the momentum of El Nino (6.0 kg) rolling along at 2 m/s. What is the change in momentum if El Nino comes to a stop? What IMPULSE would be required to do this? What force would be required to stop El Nino in 10 seconds?

  42. A 25 N force accelerates a 1200 kg car from rest to 20 m/s? What is the change in momentum Impulse? How long did it take?

  43. Which has the greater change in momentum A ball that hits and stops? or one that bounces back??

  44. Let’s look at the ball that hits and stops, Lets say it has a mass of 1 kg and is initially traveling at 1 m/s (to the right) After it stops what was the change in momentum?

  45. Now let’s look at the ball that bounces. Again 1 kg and initially moving at 1 m/s (right) and after it bounces it is moving 1 m/s (left)

  46. Which will require a greater impulse ball A ball which hits and stops or A ball that hits and bounces off An object which bounces backwards at the same speed requires twice the IMPULSE. to bring it to a stop accelerate it backwards

  47. Force Force Which will hurt more a flower pot which hits your head and breaks, or one which hits your head and bounces off? ouch continued

  48. Increasing Impulse

  49. (if needed) A 2 kg ball moving to the right at 4 m/s hits a wall and bounces to the left at 4 m/s. What is the change in momentum.

  50. Impulse momentum problems Read Sections 7-1 to 7-4 in book Answer Questions on pages 100 - 102 2, 4, 5, 7, 8, 9, 12, 19, 14, 15, 21, 24, 27, 35

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