Question

A cylinder has a radius r. To what height h should it be filled with water so that the thrust on its walls is equal to that on its bottom?  

Solution

Correct option is

h = r

 

If  is the density of water, pressure p due to height h is 

      

Now, area of the base . Therefore, thrust at the bottom is

         

Pressure p also acts on the wall. The average pressure on the wall . Surface area of wall up to . Therefore, thrust on the walls is

      

           

Now, 

      

Gives, 

      

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Q10

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