1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Why mass of spring/string assumed negligible?

  1. Sep 18, 2010 #1
    In most questions I have encountered involving the calculation of tension in spring/string/rope, we are often asked to assume that the mass of the spring/string/rope to be insignificant. Why is this so? What effect does the mass of the spring/string/rope has on the tension of the spring/string/rope? I checked a few A-level books,none offered any satisfactory explanation.
  2. jcsd
  3. Sep 18, 2010 #2

    Doc Al

    User Avatar

    Staff: Mentor

    If the spring/string/rope is massless, then the tension is uniform throughout. (Otherwise, problems become too complicated.)
  4. Sep 18, 2010 #3
    Also, if the string had mass then it would also have an acceleration when it is connected to a system. You would then be needed to write the F=Ma equation for the string also.
  5. Sep 18, 2010 #4
    If you don't mind me asking, just how complicated things can be?
  6. Sep 18, 2010 #5
    I think you'd get a differential equation that either:

    1. is much more difficult to solve, or
    2. can only be solved numerically (in current practice, with a computer)

    With massless springs, it's just sines and cosines.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - mass spring string Date
Two spring one mass Feb 16, 2017
I 2 Masses connected by a spring Aug 5, 2016
Accelerated mass on a spring Aug 26, 2015
Spring attached to string on one side, mass on the other. May 8, 2010