Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Product of Pressure (P) and time (t) has the same dimension as that of coefficient of viscosity. Reason R: Coefficient of viscosity = (Force)/(Velocity gradient) Choose the correct answer from the options given below: (a) Both A and R are true, and R is the correct explanation of A. (b) Both A and R are true but R is NOT the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true.

Answer: (c). [P t] = N/m² = Pa s, which is the SI unit of η. So A is true. Newton's law: F = η Adv/dx, so η = (F)/(A (dv/dx)), not (F)/(dv/dx). So R is false. So the answer is (c) A is true but R is false.

Given below are two statements: One is labelled as Assertion A and… | JEE Main 2022 (28 Jun, Shift 1)

Q18JEE Main 2022 · 28 JUN · SHIFT 1Easy

Viscosity & Stokes' Law

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: Product of Pressure (P) and time (t) has the same dimension as that of coefficient of viscosity.

Reason R: Coefficient of viscosity = $\frac{\text{Force}}{\text{Velocity gradient}}$

Choose the correct answer from the options given below:

Show answer and solution

Answer: (c)

$[P\,t] = \frac{\text{N}}{\text{m}^2}\cdot\text{s} = \text{Pa s}$ , which is the SI unit of $\eta$ . So A is true.
Newton's law: $F = \eta A\frac{dv}{dx}$ , so $\eta = \frac{F}{A\,(dv/dx)}$ , not $\frac{F}{dv/dx}$ . So R is false.
So the answer is (c) A is true but R is false.

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Viscosity & Stokes' Law question from JEE Main 2022 (28 Jun, Shift 1)

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