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Elevator Problem

  1. Jan 5, 2010 #1
    1. The problem statement, all variables and given/known data

    The effect of gravity is approximately 1/6 of what it is on Earth. If one were to build an elevator on the moon, (a) what would be the apparent weight of a 65kg astronaut when the elevator accelerates upward at 5 m/s2? (b) What is the acceleration of the elevator if the apparent weight of the astronaut is 500N?

    2. Relevant equations

    F = ma
    m = mass
    m = 65 kg
    w = weight
    w = mg
    a = acceleration
    a = 5 m/s2
    gM = 1.63 m/s2

    3. The attempt at a solution

    The equation I set up for (a) was: ma - mg = w
    OR (65)(5) - (65)(1.63) = w
    OR 325 - 106 = w
    Finally, w = 219N

    For (b) I had the same exact forumla: ma - mg = w
    OR (65)a - (65)(1.63) = 500
    OR 65a - 105.95 = 500
    OR 65a = 605.95
    Finally, a = 9.32 m/s2

    Just wondering, again, if this is right or not. =)
     
  2. jcsd
  3. Jan 5, 2010 #2

    PhanthomJay

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    Homework Helper
    Gold Member

    Ouch, you let the plus and minus sign bite you. The acceleration is always in the direction of the net force. The apparent weight (the normal force) and the true weight must act in opposite directions.
     
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