Question 1149626
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<pre>

In this simple case, the equilibrium condition states that the product of the weight by the length of the arm 
should be same for each side.


It gives the equation


    40 cm * 4 kg = x cm * 6.4 kg


From the equation,  x = {{{(40*4)/6.4}}} = 25.


So, the mass of 6.4 kg should be suspended at 25 cm from the middle of the bar,

i.e. in  40 - 25 = 15 cm from its other end.    <U>ANSWER</U>
</pre>

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People know this equilibrium condition just many thousand years.

Its clear mathematical formulation is attributed to Archimedes &nbsp;&nbsp;(<U><I>law of lever</I></U>).


See the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/proportions/lessons/Using-proportions-to-solve-word-problems-in-Physics.lesson>Using proportions to solve word problems in Physics</A> 

in this site.