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Roller Coaster question

  1. Dec 23, 2016 #1
    1. The problem statement, all variables and given/known data
    Jessie (m=56.2 kg) is traveling at a speed of 12.8 m/s at the top of a 19.5-m high roller coaster loop.

    a) Assuming negligible losses of energy due to friction and air resistance, determine Jessie's total mechanical energy at the bottom of the loop (h=0 m). (ans: 1.53 x 104 J)
    b) Determine Jessie's speed at the bottom of the loop. (ans: 23.4 m/s)
    c)What force does Jessie feel from her seat at the bottom of the loop? (ans: 3707N)
    2. Relevant equations
    F=ma
    ac=v2/r
    mgh
    1/2mv2
    3. The attempt at a solution
    I figured out a) with mgh+1/2mv2=Efinal.
    I figured out b) with using energy from a) 1.53 x 104= 1/2mv2
    But I can't figure out c).
    I tried using ac=23.42/19.5m to find my acceleration then multiply the mass but the number isn't close to the weight I need.
     
  2. jcsd
  3. Dec 23, 2016 #2
    It looks like you used the diameter, as opposed to the radius.
     
  4. Dec 23, 2016 #3

    TSny

    User Avatar
    Homework Helper
    Gold Member

    2nd law: Fnet = ma. Note the "net" here.
     
  5. Dec 23, 2016 #4

    gneill

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    Staff: Mentor

    Think again about what the radius of the loop is.
     
  6. Dec 23, 2016 #5
    Thanks! I totally missed that one and now my answer works!
     
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