1. Not finding help here? Sign up for a free 30min 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!

What is virtual work? And how does it apply to this question?

  1. Oct 23, 2008 #1
    Hi All!

    I am new on here so I hope you quality people can help me out:)

    I have this question and it asks me to solve it using Virtual Work? What is that and how do I apply it to this question:

    "A slender rod of length L is attached to a collar at B and rests on a portion of a circular cylinder of radius r. P and Q are two applied point loads. The effect of friction is neglected. For given L, r, P and Q, determine the value of θ corresponding to the equilibrium position of the mechanism by using the method of virtual work."


    After some research I have found the question stems from a book called: Vector Mechanics for Engineers, which I do not own!

    Thanks for your time and any help is appreciated :)
  2. jcsd
  3. Oct 25, 2008 #2
    The idea of virtual work is that you add a tiny displacement to the system along a movable point (say in this case the piston moves dx to the left as a result of the force Q), how does the position of the rod change? You know that if Q pushes left the piston by dx that this causes the rod's top end to move more vertical and thus does negative work with respect to the downward force P at that point. In order to maintain equilibrium, therefore, P must do positive work equal to this negative work as a result of Q. Your job is to find theta such that this is true for L, r, P and Q from your question.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: What is virtual work? And how does it apply to this question?
  1. Virtual work (Replies: 1)