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Homework Help: Scale in an elevator

  1. Nov 6, 2005 #1
    you are standing on a scale in an elevator. the scale reads 176lb when the elevator is at rest. the elevator begins to accelerate upward at 12ft/s^2. what is the reading of the scale?


    i converted 176lb to 80kg. i know the sum of all forces equals mass*acceleration

    but i dont know what to do next? is it N-W=ma?
     
  2. jcsd
  3. Nov 6, 2005 #2

    Doc Al

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    Staff: Mentor

    Yes, it's just Newton's 2nd law.

    Also: No need to change units. What's the acceleration due to gravity in the given units of ft/s^2?
     
  4. Nov 6, 2005 #3
    ?

    u said dont change the units but if the equation is N=ma+W what is m? do you divide 176lb by 9.8?
     
  5. Nov 6, 2005 #4

    Doc Al

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    Staff: Mentor

    What is g in units of ft/s^2 ? (Look it up if you don't know.)
     
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