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Homework Help: When an elevator moves upwards with an acceleration

  1. Oct 10, 2011 #1
    1. The problem statement, all variables and given/known data

    When an elevator moves upwards with an acceleration, what is the equation for tension?

    Is it T+W =ma?

    When an elevator moves downwards with an acceleration, would the equation be

    T+W=-ma?

    Thats all. Thanks.

    I really can't figure it out. All I know is that the equations T-mg=ma (for upwards) and T-mg=-ma (downwards) are wrong.



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Oct 10, 2011 #2

    SammyS

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    Re: Tension

    Draw a Free Body Diagram for each case. Use Fnet=ma .
     
  4. Oct 10, 2011 #3
    Re: Tension

    N = mg + ma if the elevator has an upward acceleration
    N = mg - ma if the elevator has a downward acceleration

    Would tension be the same as normal force in this situation?
     
  5. Oct 10, 2011 #4

    SammyS

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    Re: Tension

    For this problem, what is the normal force being used for?

    Draw a Free Body Diagram for each case. Use Fnet=ma .
     
  6. Oct 10, 2011 #5
    Re: Tension

    I got the problem right. Thanks for your help!
     
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