A) 33
B) 6.4
C) 72
D) 12.8
Correct Answer: C
Solution :
[c] As the sphere floats in the liquid. Therefore its weight will be equal to the upthrust force on it Weight of sphere \[=\frac{4}{3}\pi {{R}^{3}}\rho g\] ?(i) Upthrust due to oil and mercury \[=\frac{2}{3}\pi {{R}^{3}}\times {{\sigma }_{oil}}g+\frac{2}{3}\pi {{R}^{3}}{{\sigma }_{Hg}}g\] ?(ii) Equating (i) and (ii) \[\frac{4}{3}\pi {{R}^{3}}\rho g=\frac{2}{3}\pi {{R}^{3}}0.8g+\frac{2}{3}\pi {{R}^{3}}+13.6g\] \[\Rightarrow \,2\rho =0.8+13.6=14.4\Rightarrow \rho =7.2\]You need to login to perform this action.
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