Question

A flow of liquid is streamline if the Reynolds number is
A. less than 1000
B. greater than 1000
C. between 2000 to 3000
D. between 4000 to 5000

Answer 1

Hint:Lower the Reynold’s number the flow tends to be dominated by laminar flow or streamlined flow while higher the Reynold’s number the flow tends to be turbulent. It is the ratio of inertial forces to viscous force. Also relation between density , flow speed , radius of capillary and coefficient of velocity define reynold’s number.

Complete answer:
Reynold’s Number:The reynold’s number is used to categorize the fluids system in which the effect of viscosity is important in controlling the velocities and the flow pattern of a fluid.It is apure number and is dimensionless which is equal to the ratio of the inertial force per unit area to the viscous force per unit area for a flowing liquid.

There are three cases for the reynold's number:
-When $0 < K < 2000$ , the flow of the liquid through a cylindrical pipe is streamlined. $K$ less than or about $1000$.
-When $2000 < K < 3000$,the flow of liquid is variable between streamlined and turbulent.
-When $K > 3000$ ,the flow of liquid is turbulent.
As per the problem we need streamlined flow of the liquid. The reynold's number should be less than 1000.

Therefore the correct option is A.

Note:Remember as the reynold's number is defined as the ratio of same SI unit terms, it is dimensionless and unitless. This number is used to determine whether the fluid flows in laminar or turbulent . It is one of the main controlling parameters in all kinds of viscous flow. The best example for this type of flow is blood flowing throughout our body is a streamlined flow.