A Wooden Ball Of Density  is Released From The Bottom Of A Tank Which Is Filled With A Liquid Of Density  up To A Height h1. The Ball Rises In The Liquid, Emerges From Its Surface And Attains A Height h2 in Air. If Viscous Effects Are Neglected, The Ratio h2/h1 is   

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Question

A wooden ball of density  is released from the bottom of a tank which is filled with a liquid of density  up to a height h1. The ball rises in the liquid, emerges from its surface and attains a height h2 in air. If viscous effects are neglected, the ratio h2/h1 is   

Solution

Correct option is

 

Weight of the ball

      

Upthrust 

Therefore, the net upward force acting on the ball is  

        

Now, mass of the ball is . Therefore, upward acceleration of the ball while it is rising in the liquid is  

        

            

            

Velocity of the ball on reaching the surface of water is  

          

This is the initial upward velocity of the ball in air. If it rises to a height h2in air, we have   

             

Equating (i) and (ii), we have a h1 = g h2

  

              

              .

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