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9-1.Fluid Mechanics
medium
An empty balloon weighs $1\, g$. The balloon is filled with water to the neck and tied with a massless thread. The weight of balloon alongwith water is $101\, g$. The balloon filled with water is weighed when fully immersed. Then, its weight in water is ...... $g$
A
$1 $
B
$101 $
C
$201 $
D
$51 $
Solution
Mass of empty balloon $=1 \mathrm{g}$
mass of balloon filled with water $=101 \mathrm{g}$
mass of water $=100 \mathrm{g}=\mathrm{V}_{\text {balloon }} \rho_{\mathrm{\omega}}$
when balloon is immersed in water
effective weight $=$ weight $-$ Buoyancy
$=(101) \mathrm{g}-\mathrm{V}_{\mathrm{balloon}} \rho_{\mathrm{\omega}} \mathrm{g}$
$=(101) \mathrm{g}-(100) \mathrm{g}=1 \mathrm{g}$
weight $=1 \mathrm{g}$
Standard 11
Physics
