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Physics - Fluid Question with Solution | TestHub

PhysicsFluidViscosityMedium2 minQB

PhysicsMediumsingle choice

During a coating process, a thin, flat tape of width w is pulled through a channel of length L containing a Newtonian fluid of density $ρ$ and dynamic viscosity $μ$ . The fluid is in contact with both sides of the tape. Estimate the force required to pull the tape through the channel if the tape has velocity V and the channel has height H. You may assume that the tape is much thinner than H.

Options:

Answer:

Solution:

Newton's law of viscosity on each side of the tape, with the velocity changing from V to 0 across a gap H/2: $F_{1} = μ (w L) \frac{V}{H /2}$

Fluid touches both sides, so $F = 2 F_{1} = 2 μ w L \frac{2 V}{H} = \frac{4 μ V L w}{H}$ hence (A).

Stream:JEESubject:PhysicsTopic:FluidSubtopic:Viscosity

⏱ 2mℹ️ Source: QB

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