Physics - Fluid Question with Solution | TestHub

PhysicsFluidViscosityMedium2 minPYQ_2021
PhysicsMediumsingle choice

A raindrop with radius R=0.2 mm falls from a cloud at a height h=2000 m above the ground. Assume that the drop is spherical throughout its fall and the force of buoyance may be neglected, then the terminal speed attained by the raindrop is : [Density of water fw=1000 kg m-3 and Density of air fa=1.2 kg m-3, g=10 m/s2 Coefficient of viscosity of air =1.8×10-5N s m-2

Options:

Answer:
C
Solution:

At terminal speed

a=0

Fnet=0

mg=Fv=6πηRv

V=mg6πηRV

v=ρw4π3R3 g6πηR

=2ρwR2 g9η

=40081 m/s

=4.94 m/s

Stream:JEESubject:PhysicsTopic:FluidSubtopic:Viscosity
2mℹ️ Source: PYQ_2021

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