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Saturday, 15 December 2012

Problem No.4.3:- Ten bricks, each 6.0 cm thick mass 1.5kg, lie flat on a table. How much work is required to stack them one on the top of another?


Problem No.4.3:-  Ten bricks, each 6.0 cm thick mass 1.5kg, lie flat on a table. How much work is required to stack them one on the top of another?
Solution:-
Given Data:-
To Determine:-
    Work done by placing them one on the top of another = W =?
Calculation:-
   Now first of all suppose that all bricks are on the ground. Now you lift a brick i.e.; 2nd and placed it on any one of them which is 1st, now they are two bricks, after that you lift a third one and placed it on the other two, and so on.
Now think for a while that when you lift 2nd brick and placed it 1st brick then 1st brick remain on its place and you never do any work to lift it.
So, we conclude that we work done only on 9 bricks and not on the 10th which is basically the 1st brick.
          Hence,            
                                             Total weight of 9 bricks = w = mg
 After that when you manage the all of these bricks then, their height is 60cm but their combined center of gravity is 30cm.      





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