Two masses $m_1$ and $m_2$ are connected by a spring of spring constant $k$ and slide freely without friction along horizontal track. What is period of oscillation? No force influence.

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    $\begingroup$ Hi user1872329. Welcome to Physics.SE. This site deals with conceptual Physics Q&A. We don't encourage homework questions that doesn't involve any sort of work done by the author and asks other users to solve the problem. If you think you could clarify your question, add what you've done along with your question. We're ready to help you. If you aren't clear, Please have a look at our homework policy for more info. $\endgroup$ Apr 25, 2013 at 13:45
  • $\begingroup$ Have you tried anything? Can you show us at least a force balance or some effort to get an answer? $\endgroup$ Apr 25, 2013 at 13:59
  • $\begingroup$ You should do a dynamic analysis of the system and find the reduced mass of the system.Or you can work with energies(o.5(m1+m2)*V^2=0.5Kx^2.From there you should find the velocity and proceed in finding the time that it gets to do a whole oscilation. $\endgroup$ Mar 23, 2015 at 0:51

1 Answer 1


Use Reduced Mass to tackle such problems.

Now just see this as a simple spring mass system with mass as reduced mass like this one. Where the hanging mass is equivalent reduced mass.

enter image description here

  • $\begingroup$ Starting the solution this problem from the reduction of masses is not the best idea. It is necessary to write equations of dynamics first. $\endgroup$
    – freude
    Apr 25, 2013 at 13:47
  • $\begingroup$ Hmm.. I have never been able to complete it using equations myself without mistake .So, i don't suggest it. :P $\endgroup$
    – ABC
    Apr 25, 2013 at 13:50

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