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Physics - Fluid Question with Solution | TestHub

PhysicsFluidViscosityEasy2 minPYQ_2020

PhysicsEasysingle choice

A ball of radius r and density ρ falls freely under gravity through a distance h before entering water. Velocity of ball does not change even on entering water. If viscosity of water is η, the value of h is given by

Options:

Answer:

Solution:

Velocity of ball when the water surface

$v = \sqrt{2 gh} ............ (i)$

Terminal velocity of ball inside the water

$v = \frac{2}{9} r^{2} g \frac{(ρ - 1)}{η} ............ (i i)$

Equating (i) and (ii)we get $\sqrt{2 gh} = \frac{2}{9} \frac{r^{2} g}{η} (ρ - 1) \Rightarrow h = \frac{2}{81} r^{4} (\frac{ρ - 1}{η})^{2} g$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:FluidSubtopic:Viscosity

⏱ 2mℹ️ Source: PYQ_2020

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