Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Question on strain?

  1. Nov 5, 2004 #1
    I'm having a real problem with this question, could someone please give me a hand?

    A 1260kg freight elevator is supported by a steel cable of diameter 34.9mm. It is loaded with a crowd of people collectively having a mass of 2850kg and it is descending.

    a) What is the strain on the cable while the elevator is descending at the constant speed of 2.30 m/s?

    b) What is the strain in the cable when it is brought to a stop in 0.600s?

    I THOUGHT i was okay with this question at first.... but then i realized that i had totally ignored the fact that the elevator is moving downwards! :surprised I don't know what i need to do to factor that in?? Help!
    Last edited: Nov 5, 2004
  2. jcsd
  3. Nov 5, 2004 #2

    Doc Al

    User Avatar

    Staff: Mentor

    first find the tension

    The first step, in each case, is to find the tension in the cable. To do that, indentify the forces acting the elevator car (there are only two) and apply Newton's 2nd law.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook