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Physics - Fluid Question with Solution | TestHub

PhysicsFluidViscosityEasy2 minPYQ_2020

PhysicsEasysingle choice

A solid ball of density $ρ_{1}$ and radius $r$ falls vertically through a liquid of density $ρ_{2}$ . Assume that the viscous force acting on the ball is $F = k r v$ , where $k$ is a constant and $v$ its velocity. What is the terminal velocity of the ball?

Options:

Answer:

Solution:

Net force on the ball $= 0$

(when terminal velocity is attained).

Hence,

Weight=upthrust+viscous force

$∴ \frac{4}{3} π r^{3} ρ_{1} g = \frac{4}{3} π r^{3} ρ_{2} g + k {rv}_{T}$

$∴ v_{T} = \frac{4 π g r^{2}}{3 k} (ρ_{1} - ρ_{2})$

Stream:NTA_ABHYAS_NEETSubject:PhysicsTopic:FluidSubtopic:Viscosity

⏱ 2mℹ️ Source: PYQ_2020

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