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.; 2^nd and placed it on any one of them which is 1^st, 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 2^nd brick and placed it 1^st brick then 1^st 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 10^th which is basically the 1^st 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.