JEE Main & Advanced Sample Paper JEE Main - Mock Test - 5

  • question_answer
    A body floats in water with one-third of its volume above the surface of water. If it is placed in oil, it floats with half of its volume Max. Marks: 300 above the surface of the oil. The specific gravity of oil is

    A) \[\frac{5}{3}\]              

    B) \[\frac{4}{3}\]

    C) \[\frac{3}{2}\]              

    D) 1

    Correct Answer: B

    Solution :

    [b]: When the body is floating in a liquid, then Weight of the body = Weight of liquid displaced i.e.\[{{V}_{body}}{{\rho }_{body}}g={{V}_{inside}}{{\rho }_{liquid}}g\] Let V be the volume of the body. In water, \[V{{\rho }_{body}}g=\frac{2}{3}{{\rho }_{water}}g\] \[{{\rho }_{body}}=\frac{2}{3}{{\rho }_{water}}\]                                             ....(i) In oil,\[V{{\rho }_{body}}g=\frac{1}{2}V{{\rho }_{oil}}g\] \[{{\rho }_{body}}=\frac{1}{2}{{\rho }_{oil}}\]                                     ....(ii) From (i) and (ii) we get\[\frac{{{\rho }_{oil}}}{{{\rho }_{water}}}=\frac{4}{3}\] Specific gravity of oil\[\frac{{{\rho }_{oil}}}{{{\rho }_{water}}}=\frac{4}{3}\]


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