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Question

If dimensions of critical velocity vcv_c of a liquid flowing through a tube are expressed as [ηxρyrz][\eta^x \rho^y r^z], where η\eta, ρ\rho and rr are the coefficient of viscosity of the liquid, the density of liquid and radius of the tube respectively, then the values of xx, yy and zz are given by

A

1,1,11, -1, -1

B

1,1,1-1, -1, 1

C

1,1,1-1, -1, -1

D

1,1,11, 1, 1

Step-by-Step Solution

Let the dimensional formula of critical velocity vcv_c be related to coefficient of viscosity η\eta, density ρ\rho, and radius rr as: [vc]=[η]x[ρ]y[r]z[v_c] = [\eta]^x [\rho]^y [r]^z Substituting the dimensions of each quantity: Dimension of velocity, vc=[LT1]v_c = [L T^{-1}] Dimension of coefficient of viscosity, η=[ML1T1]\eta = [M L^{-1} T^{-1}] Dimension of density, ρ=[ML3]\rho = [M L^{-3}] Dimension of radius, r=[L]r = [L]

[M0L1T1]=[ML1T1]x[ML3]y[L]z[M^0 L^1 T^{-1}] = [M L^{-1} T^{-1}]^x [M L^{-3}]^y [L]^z [M0L1T1]=[Mx+yLx3y+zTx][M^0 L^1 T^{-1}] = [M^{x+y} L^{-x-3y+z} T^{-x}]

Equating the powers of MM, LL, and TT on both sides, we get: For MM: x+y=0    y=xx + y = 0 \implies y = -x For TT: x=1    x=1-x = -1 \implies x = 1 Since x=1x = 1, we have y=1y = -1. For LL: x3y+z=1    (1)3(1)+z=1    1+3+z=1    2+z=1    z=1-x - 3y + z = 1 \implies -(1) - 3(-1) + z = 1 \implies -1 + 3 + z = 1 \implies 2 + z = 1 \implies z = -1

Therefore, the values of x,yx, y and zz are 1,1,11, -1, -1 respectively.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from UNITS AND MEASUREMENTS. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSUNITS AND MEASUREMENTSdimensionscriticalvelocityliquidflowing

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