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PhysicsUnit & DimensionMiscellaneousMedium2 minPYQ_2015
PhysicsMediumsingle choice

A beaker contains a fluid of densityρkgm3, specific heatSJkgoCand viscosityη. The beaker is filled up to height h. To estimate the rate of heat transfer per unit areaQ˙Aby convection when beaker is put on a hot plate, a student proposes that it should depend onη,SΔθhand1ρgwhenΔθ(inoC) is the difference in the temperature between the bottom and top of the fluid. In that situation the correct option forQ˙Ais:

Options:

Answer:
A
Solution:

QA=ηxsθhy1ρgz. . . (1)

QA=MT-3,η=ML-1T-1

sθh=LT-2,1ρg=M-1L2T2

MT-3=MxL-xT-xLyT-2yM-2L2zT2z

MT-3=Mx-zL-x+y+2zT-x-2y+2z

So1=x-z. . . (2)

-x+y+2z=0. . . (3)

-x-2y+2z=-3. . . (4)

from 2, 3, 4

x=1, y=1, z=0from (1)

soQA=η sθh

Stream:JEESubject:PhysicsTopic:Unit & DimensionSubtopic:Miscellaneous
2mℹ️ Source: PYQ_2015

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