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Homework Help: Roller coaster minimum speed around loop and effective weight

  1. Oct 13, 2009 #1
    1. The problem statement, all variables and given/known data
    A roller coaster goes around a vertical loop of 20.0m. a) What is the minimum speed the cars must be moving so that the passengers do not fall out at the top? b) Assuming that the car maintains the same constant speed what is th effective weight of the passengers at the bottom? c) Again assuming car maintains this same constant speed, what is the net force (magnitutde and direction) acting on a 25kg passenger at point half way down the loop?

    2. My attempt at solution

    a) At top, N -> 0
    N + mg = m(v2/r)
    vmin=sqrt(rg) = 14 m/s

    b) At bottom, N counters mg
    N - mg = m(v2/r)
    N = m((v2/r) + g)
    N = m (9.8 + g) = 19.6m or 2mg

    c) I had no idea what to do here?
  2. jcsd
  3. Oct 13, 2009 #2


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    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi and9! Welcome to PF! :smile:
    Same as a) and b) … find N, and add it (as a vector) to the weight. :wink:
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