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Homework Help: What is the tension on the line when the elevator is accelerating

  1. Mar 21, 2006 #1
    An elevator weighs 10000N. What is the tension on the line when the elevator is accelerating upwards at 3 m/s?

    I don't know how to go about this one. Any help?
  2. jcsd
  3. Mar 21, 2006 #2
    Well, acceleration is in [itex] \frac {m}{s^2} [/tex]. Is that a typo? Also, what is newtons first law?
  4. Mar 22, 2006 #3
    And after you recall Newton's first law, be sure to draw a force diagram before solving the problem. This will help ensure that you get the signs correct (arrows pointing in opposite directions will have opposite signs).
  5. Mar 22, 2006 #4


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    I agree with drawing a free body diagram (this should always be the first step in that type of question) but I think that everybody meant Newton's *second* law...

  6. Mar 22, 2006 #5


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    I'm sorry to be pedantic but the units of acceleration are not [itex]m/s[/itex], they are [itex]m/s^2[/itex].

    There are two questions that you should ask yourself when doing this question;

    (1) What is the tension in the wire when the elevator is stationary? I.e. what force is required to balance the weight of the elevator?

    (2) What additional force is required to accelerate the elevator at [itex]3 m/s^2[/itex]? Hint: For this one you will need to use Newton's second law as nrqed said.

    Hope this helps
  7. Mar 22, 2006 #6
    Whoops. I was like a sheep, following right over the edge of a cliff.
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