# Equilibrium of Forces

1. Apr 7, 2013

### Arabell

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 .

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2. Apr 7, 2013

### FermionXLR8r

Solution

First we must take the vertical component of the tension forces acting on the mirror. Let the mass of mirror be m
Then
2TSin45=mg
solve for T by substituting the values.
A modification which can be made is connecting the strings parallely

3. Apr 7, 2013

### Arabell

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

4. Apr 7, 2013

### haruspex

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?