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9-1.Fluid Mechanics
hard
A piece of copper having an internal cavity weights $264\, g$ in air and $221\, g$ in water. Find volume (in $cc$) of cavity. Density of $Cu = 8.8\, g/cc$
A
$30$
B
$20$
C
$43$
D
$13$
Solution
Thrust $\mathrm{Th}=\mathrm{V} \sigma \mathrm{g}$
Vol. of body $V=\frac{(264-221) g}{1 \times g}=43 \mathrm{cc}$
volume of material
$=\frac{\text { mass of body }}{\text { density }}=\frac{264}{8.8}=30 \mathrm{cc}$
vol. of cavity $=(43-30) \mathrm{cc}=13 \mathrm{cc}$
Standard 11
Physics