A wooden block of mass m and density  is tied to a string; the other end of the string is fixed to the bottom of a tank. The tank is filled with a liquid of density . What is the tension in the string. 


Correct option is

Volume of the block . Now upthrust = weight of water displaced = weight of volume  of liquid = mass of volume . This is the upward force on the block due to buoyancy. The downward force on the block = its weight = mg. The tension in the string is the net upward force on the block which is     





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