# JNTU Question Papers

## Mechanics Of Fluids I Sem Nov 2008

1. (a) The weight of 8 m3 of a certain oil is 64 KN. Calculate its specific weight,mass density and specific gravity

(b) The weight of an object measured on ground level where g = 9.81 m/sec2 is

35,000 N. Calculate its weight at the following locations

i. Moon gm = 1.62 m/sec2

ii. Sun, gs=274.68 m/sec2

iii. Mercury, gme = 3.53 m/ sec2

iv. Jupiter, gj= 26.0 m/sec2

v. Saturn, gsa = 11.2 m/sec2 and

vi. Venus, gv = 8.54 m/sec2.

Also find the mass density of the object on these planets [8+8]

2. (a) Derive three dimensional continuity equation.

(b) The x and y components in a three dimensional flow are given by

U = x2 + z2 ? = y2 + z2

Find the simplest z ? component of velocity that satisfies the continuity equa-

tion. [8+8]

3. (a) Derive Euler’s equation of motion for a fluid flow..

(b) A jet of water issues from 20 mm dia fire hose at the end of which a 5.0mm diameter nozzle is fixed. If pressure at inlet of the nozzle is 200 kN/m2, determine force exerted by nozzle on the flow. [8+8]

4. (a) Why is it necessary to control the growth of boundary layer on most of the

bodies? What methods are used for such a control?

(b) A sphere has a projected area of 1m2. Compare the drag force in water and in air when travelling at a speed of 30 km/hr. [8+8]

5. (a) What is the function of wind tunnel?

(b) What is meant by stagnation point. Explain [8+8]

6. (a) Sketch the Reynolds apparatus and explain how the laminar flow can be demonstrated with the help of this apparatus.

(b) A viscous liquid was flowing in laminar regime in a 6 cm diameter circular pipe. A pitot tube at a radial distance of 2 cm from the axis indicated a velocity of 0.6 m/sec. Calculate the maximum velocity, the mean velocity and the discharge in the pipe. [8+8]

7. (a) Obtain an expression for the optimum exit diameter of a nozzle to be fitted

at the service end of a pipe for maximum power transmission.

(b) Find the loss of head when a pipe of diameter 20 cm is suddenly enlarged to

a diameter of 40cm. The rate of flow of water through the pipe is 250lit/sec.

[8+8]

8. (a) The rate of flow of water in a 150mm diameter pipe is measured with a ven-

turimeter with a 50mm dia. throat. When a mercury manometer is connected across the converging section reads 8mm, the flow rate is 2.7 kg/s. What is the coefficient of discharge at that flow rate and what is permanent loss of head? Specific gravity of mercury = 13.6

(b) What is the device used for measuring fluid pressure? Explain briefly the principle of an inclined Manometer.