# Flow of Liquids Numerical on Viscosity Poiseuille’s Formula and Reynold’s Number Class-11 Nootan ISC Physics

Flow of Liquids Numerical on Viscosity Poiseuille’s Formula and Reynold’s Number Class-11 Nootan ISC Physics Solutions Ch-15. Step by step Solutions of Kumar and Mittal Physics of Nageen Prakashan as council latest prescribe guideline for upcoming exam. Visit official Website for detail information about ISC Board Class-11 Physics.

## Flow of Liquids Numerical on Viscosity Poiseuille’s Formula and Reynold’s Number Class-11 Nootan ISC Physics

 Board ISC Class 11 Subject Physics Writer Kumar and Mittal Publication Nageen Prakashan Chapter-15 Flow of Liquids Topics Numericals on Viscosity, Poiseuille’s Formula and Reynold’s Number Academic Session 2024-2025

### Numericals on Viscosity, Poiseuille’s Formula and Reynold’s Number

##### Que-19: There is a 1 mm thick layer of oil between a flat plate of area 10^-2 m² and a big plate. How much force is required to move the plate with a velocity of 1.5 cm/s. The coefficient of viscosity of oil is 1 poise.

Ans- F = η A v / l

=> (1 x 10^-1 x 10^-2 x 1.5 x 10^-2) / (1 x 10^-3)

=> 1.5 x 10^-2 N

##### Que-20: A square plate of 10 cm side moves parallel to another plate with a relative velocity of 10 cm/s, both plates immersed in water. If the viscous force is 2 x 10³ N, calculate the perpendicular distance between the plates.

Ans- F = η A v / l

=> l = η A v / F

=> [0.001 x (0.1 x 0.1) x 10 x 10^-2] / (2 x 10^-3)

=> 0.05 x 10^-2 m = 0.05 cm

##### Que-21: Water is flowing through a horizontal tube 4 km in length and 4 cm in radius at a rate of 20 liter/sec. Calculate the pressure required to maintain the flow in terms of the height of mercury column.

Ans- According to Poiseuille’s Formula

Q = π p r^4 / 8 η l

p = Q . 8 η l / π r^4

=> [20 x 10^-3 x 8 x 0.001 x 4000] / [3.14 x (4 x 10^-2)^4]

=> (20 x 8 x 4 x 10^-3) / (3.14 x 256 x 10^-8)

=> 0.8 x 10^5 pa

if height of mercury column is h

then h ρ g = 0.8 x 10^5

=> h = (0.8 x 10^5) / (13.6 x 10³ x 9.8)

=> 0.006 x 10²

=> 0.6 m = 60 cm

##### Que-22: The level of blood in a bottle used to give blood to a patient is 1.3 m high above the needle which is 3 cm in length and has an internal diameter of 0.36 mm. If 4.5 cm³ of blood is passing through the needle per minute, calculate the viscosity of blood. The density of blood is 1020 kg/m³. Ignore fall in the level of blood in the bottle.

Ans- Q = π p r^4 / 8 η l

η =  π p r^4  / 8 Q l

=> [3.14 x 1.3 x 1020 x 9.8 x (0.18 x 10^-3)^4] / (8 x 4.5 x 10^-6 x 3 x 10^-2)

=> 2.38 x 10^-3 N-s/m²

—:  end of Flow of Liquids Numerical on Viscosity Poiseuille’s Formula and Reynold’s Number Class-11 :—

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