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Equilibrium of Forces

  1. Apr 7, 2013 #1
    1. The problem statement, all variables and given/known data

    Diagram 4 shows a 2 kg mirror hung on a wall using strings of the same length . The mirror is in equilibrium state.

    a) On Diagram 4 , label the force that act on the mirror .

    b) Calculate the tension of the string , T that act on the mirror .

    c) Suggest a modification to be made so that the string can withstand a larger maximum force .

    2. Relevant equations

    3. The attempt at a solution

    I had only drawn a free body diagram and I am already stuck and don't know what to do... Help me please , any solution to this question would be greatly aprreciated .

    Attached Files:

  2. jcsd
  3. Apr 7, 2013 #2

    First we must take the vertical component of the tension forces acting on the mirror. Let the mass of mirror be m
    solve for T by substituting the values.
    A modification which can be made is connecting the strings parallely
  4. Apr 7, 2013 #3
    Thanks mate for replying ..... In the equation , where does 2 come from , does it come from the mirror which is 2 kg since it is an equilibrium state . Another thing is can you explain why connecting the strings parallely enables it to withstand a larger maximum force
  5. Apr 7, 2013 #4


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    The 2 is because there are two strings. If the tension is T, each each string is supplying an upwards force of T sin (45) = T/√2. Since that balances the weight of the mirror, what is T?

    If the strings were vertical with tension U, what would the equation be?
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