JEE MAIN - Physics (2022 - 26th June Evening Shift - No. 6)

If p is the density and $$\eta$$ is coefficient of viscosity of fluid which flows with a speed v in the pipe of diameter d, the correct formula for Reynolds number Re is :
$${R_e} = {{\eta d} \over {\rho v}}$$
$${R_e} = {{\rho v} \over {\eta d}}$$
$${R_e} = {{\rho vd} \over \eta }$$
$${R_e} = {\eta \over {\rho vd}}$$

Explanation

The Reynolds number (Re) is a dimensionless quantity used in fluid mechanics to predict the onset of turbulence. It is defined as:

$$Re = \frac{{\rho v d}}{{\eta}}$$

where:

  • $\rho$ is the fluid density
  • $v$ is the fluid velocity
  • $d$ is a characteristic linear dimension (for a pipe, this is typically the diameter)
  • $\eta$ is the dynamic viscosity of the fluid

So, Option C is the correct answer:

$${R_e} = {{\rho vd} \over \eta }$$

Comments (0)

Advertisement