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How to get initial and final velocity? need help thanks

  1. Aug 4, 2012 #1
    1. The problem statement, all variables and given/known data
    a human cannonball in 1940 soared over three ferris wheels, each 18 meters high covering a horizontal distance of 10.63 meters. Assuming that the point of projection is 2.50 meters above the ground and that he landed safely on a net placed at the same level, find his initial velocity. Assuming that he missed the net and landed on the ground, with what velocity will he strike the ground?


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Aug 4, 2012 #2
    up for today...
     
  4. Aug 4, 2012 #3
    up for today...
     
  5. Aug 4, 2012 #4
    If no more conditions are given, it seems that the problem requires that you find an optimal setup for the stunt, optimal in the sense that the initial velocity is minimal.
     
  6. Aug 5, 2012 #5
    i dont understand how... can you teach me how?
     
  7. Aug 5, 2012 #6

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    You have made no attempt at all, not even citing equations that might be relevant. Are you saying that you are taking a course in which this was given as an exercise and have learned nothing about this?
     
  8. Aug 5, 2012 #7
    Imagine it is you who will be fired from a cannon in order to fly over three ferris wheels. You are in full control of the arrangement. How would you approach the problem?
     
  9. Aug 6, 2012 #8
    1. The problem statement, all variables and given/known data
    a human cannonball in 1940 soared over three ferris wheels, each 18 meters high covering a horizontal distance of 10.63 meters. Assuming that the point of projection is 2.50 meters above the ground and that he landed safely on a net placed at the same level, find his initial velocity. Assuming that he missed the net and landed on the ground, with what velocity will he strike the ground?


    2. Relevant equations
    my problem i dont know what equation il use.... coz there so many missing values
    is the initial velocity is 0?


    3. The attempt at a solution
    this is what i did, i know its not right i hjope you guys could help me out...
    “Y=Viy * t + 0.5 * Ay * t^2 “ to solve for time
    -20.50m = (0 m/s) * t + 0.5 (-9.8 m/s/s) * t^2
    -20.50m = (-4.9 m/s/s) * t^2
    4.1s^2 = t^2
    (TIME) T= 2.02s

    Answer:
    Problem 1:Initial velocity is 0

    Problem 2: Assuming that he missed the net and landed on the ground, with what velocity will he strike the ground?

    V= distance/time
    V=10.63/2.02s
    V=5.26m/s
     
  10. Aug 6, 2012 #9
    up for today...
     
  11. Aug 6, 2012 #10
    up for today...
     
  12. Aug 6, 2012 #11
    It depends on the horizontal distance of the cannon and the first wheel, and the last wheel with the safety net.
     
  13. Aug 6, 2012 #12
    how would i know? those are the only values i have... does this mean this problem cannot be solve?
     
  14. Aug 6, 2012 #13
    An initial velocity of zero makes no sense. He wouldn't go anywhere. Can you decide where he might have to be at some point in space? Like as he approaches the first wheel?
     
  15. Aug 6, 2012 #14
    You may need to make an assumption about the placement of the first Ferris wheel and its distance from the cannon.
     
  16. Aug 6, 2012 #15
    what do you mean? how to decide?
     
  17. Aug 6, 2012 #16
    can anyone help me solve this?
     
  18. Aug 6, 2012 #17
    would really appreciate the effort ... thanks
     
  19. Aug 6, 2012 #18
    Is a drawing included? The orientation and position of the wheels will be important. If no drawing is included you will need to start the problem making an assumption about where the wheels are.
     
  20. Aug 6, 2012 #19
    You can find the velocity for maximum range, the distance between the wheels.
    For maximum range the angle at above first wheel is 45°.
     
  21. Aug 6, 2012 #20
    up for today...
     
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