(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The lenght of a 2mm diameter steel wire CD has been adjusted so that with no load applied a gap of 1.5mm exists between end B of the rigid beam ACB and a contact point E. Knowing E = 200GPa, determine where the 20kg block should be placed on the beam in order to cause contact between B and E

http://tinypic.com/r/11lnexu/6

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2. Relevant equations

Summation of Forces

Deformation = Load*Lenght/ Area*Modulus of Elasiticty

slope of a line

3. The attempt at a solution

My approach is as follows, first see how far the wire must stretch to allow the beam to become in contact with the surface. Since the Beam is rigid it must form a straigth line and using that knowledge I found that the wire must elongate by .3mm. With that information I was going to plug the deformation and solve for force which gave me a large number of 753N required to stretch the wire that much....

Now my problems begin. I have reaction at A due to the pin and 20kg box which results in a 196N force. So with a force balance in the Y axis I can find all the forced but this where I am stuck how do I find out where the box go. Why does it matter? I am not sure how the moment plays a role but I know that must be the key. Am I supposed to find the position whichs moments are all zero? I am not sure how the placement affects this question since the elongation is driven by the axial load.

I am supposed to be solving for x to place the block. I feel confident about the elogation and hence the force required on the wire. From there I need a push to finish this

Any help is much appreciated

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# Homework Help: Mech of Materials stretching wire problem

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