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Homework Help: Angular vs Radial Acceleration

  1. Apr 17, 2015 #1
    1. The problem statement, all variables and given/known data
    The cosmoclock 21 Ferris Wheel in Yokohama City, Japan, has a diameter of 100m. Its name comes from its 60 arms, each of which can function as a second hand (so it makes one revolution every 60.0s).

    a) Find the speed of the passengers when the Ferris wheel is rotating at this rate [No problem]
    b) A passenger weighs 882N at the weight-guessing booth on the ground. What is his apparent weight at the lowest point of the ferris wheel?

    2. Relevant equations
    d = vt
    arad = v^2.r
    w = mg

    3. The attempt at a solution
    I have no problem with part a.

    distance = 2pi r = 314.1m
    velocity = 314.1/60 = 5.235m/s

    It is part b where I get confused. I get it right till the step to use acceleration. I use radial acceleration and get it wrong, googled the question and someone used angular acceleration. I used his angular acceleration value and my answer was correct. But I am wondering why use angular acceleration instead of radial?

    Weight on ground = 882N
    Mass = 89.9 kg

    F = ma
    Nb - mg = ma
    Nb = m (a +g)

    *This is the part where I use radial acceleration
    a = v2/r
    a = 0.1745m/s2

    Nb = 89.9 (0.1745+9.81)
    Nb = 897.6N
  2. jcsd
  3. Apr 17, 2015 #2


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    Homework Helper

    Hi, welcome to physicsforums :)
    the equation you are using a=v2/r is the correct one. And your value for the velocity is good. I think you made a mistake in doing the calculation v2/r. what values did you use? Remember you should be using radius, not diameter.
  4. Apr 17, 2015 #3
    Hey Bruce! Haha you are right! Opps!! Thank you!
  5. Apr 17, 2015 #4


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    Homework Helper

    no worries! glad to help :) Your method was good.
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