# Basic Introduction

1. Newton’s law of viscosity depends upon the

(a) stress and strain in a fluid

(b) shear stress, pressure and velocity

(c) shear stress and rate of strain

(d) viscosity and shear stress

2. The shear stress developed in lubricating oil, of viscosity 9.81 poise, filled between two parallel plates 1cm apart and moving with relative velocity of 2 m/s is

(a) 20N/m2

(b) 196.2N/m2

(c) 29.62N/m2

(d) 40N/m2

3. What are the dimensions of kinematic viscosity of a fluid?

(a) LT-2

(b) L2T-1

(c) ML-1T-1

(d)ML-2T-2

4. An oil of specific gravity 0.9 has viscosity of 0.28 Strokes at 380ºC. What will be its viscosity in N-s/m2?

(a) 0.2520

(b) 0.0311

(c) 0.0252

(d) 0.0206

5. Decrease in temperature, in general, results in

(a) An increase in viscosities of both gases and liquids

(b) A decrease in the viscosities of both liquids and gases

(c) An increase in the viscosity of liquids and a decrease in that of gases

(d) A decrease in the viscosity of liquids and an increase in that of gases

6. Assertion (A): In general, viscosity in liquids increases and in gases it decreases with rise in temperature.
Reason (R): Viscosity is caused by intermolecular forces of cohesion and due to transfer of molecular momentum between fluid layers; of which in liquids the former and in gases the later contribute the major part towards viscosity.

(a) Both A and R are individually true and R is the correct explanation of A

(b) Both A and R are individually 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

### Surface Tension

7. Surface tension is due to

(a)Viscous forces

(b)Cohesion

(d)The difference between adhesive and cohesive forces

8. The dimensions of surface tension is

(a) N/m2

(b) J/m

(c) J/m2

(d) W/m

9. If the surface tension of water-air interface is 0.073 N/m, the gauge pressure inside a rain drop of 1 mm diameter will be:

(a) 0.146 N/m2

(b) 73 N/m2

(c) 146 N/m2

(d) 292 N/m2

10. What is the pressure inside a soap bubble, over the atmospheric pressure if its diameter is 2 cm and the surface tension is 0·1 N/m?

(a) 0·4 N/m2

(b) 4·0 N/m2

(c) 40.0 N/m2

(d) 400.0 N/m2

### Capillarity

Which one of the following is correct?

11. The capillary rise on depression in a small diameter tube is

(a) Directly proportional to the specific weight of the fluid

(b) Inversely proportional to the surface tension

(c) Inversely proportional to the diameter

(d) Directly proportional to the surface area

12. The capillary rise at 20ºC in clean glass tube of 1 mm diameter containing water is approximately

(a) 15 mm

(b) 50 mm

(c) 20 mm

(d) 30 mm

A capillary tube is inserted in mercury kept in an open container.
13. Assertion (A): The mercury level inside the tube shall rise above the level of mercury outside.
Reason (R): The cohesive force between the molecules of mercury is greater than the adhesive force between mercury and glass.

(a) Both A and R are individually true and R is the correct explanation of A

(b) Both A and R are individually 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

14. Assertion (A): A narrow glass tube when immersed into mercury causes capillary depression, and when immersed into water causes capillary rise.
Reason (R): Mercury is denser than water.

(a) Both A and R are individually true and R is the correct explanation of A.

(b) Both A and R are individually 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.

15. Which Property of mercury is the main reason for use in barometers?

(a) High Density

(b) Negligible Capillary effect

(c) Very Low vapour Pressure

(d) Low compressibility