Fluid Dynamics MCQs

Question 1

Bermoulli's equation can be derived from the conservation of:

Accepted Answer

Energy

Answer

Mass

Answer

Volume

Answer

Pressure

Question 2

One end of the cylindrical pipe has a radius of 1.5cm. If water streams (density=1.0 x 10^3kg/m3) steadily out of it at 7.0m/s, the volume rate is:

Accepted Answer

4.9 x 10^-3 m3/s

Answer

4.9 m3/s

Answer

7.0 m3/s

Answer

49 m3/s

Question 3

An ice berg of density 900 Kg/m3 is floating in water of density 1000 Kg/m3 The percentage of volume of ice-cube outside the water is:

Accepted Answer

10%

Answer

20%

Answer

35%

Answer

25%

Question 4

In which one of the following cases will the liquid flow in a pipe be most streamlined?

Accepted Answer

Liquid of high viscosity and low density flowing through a pipe of small radius

Answer

Liquid of high viscosity and high density flowing through a pipe of small radius

Answer

Liquid of low viscosity and low density flowing rough a pipe of large radius

Answer

Liquid of low viscosity and high density flowing through a pipe of large radius

Question 5

Two water pipes of diameters 2 cm and 4 cm are connected with the main supply. The velocity of flow of water supply line in the pipe of 2 cm diameter is:

Accepted Answer

The velocity is 4 times that in the other pipe

Answer

The velocity is 1/4 times that in the other pipe

Answer

The velocity is 2 times that in the other pipe

Answer

The velocity is 1/2 times that in the other pipe

Question 6

Water enters through end A with speed v1 and leaves through end B with speed v2 of a cylindrical tube AB. The tube is always completely filled with water. In case I tube is horizontal and in case II it is vertical with end A upwards and in case III it is vertical with end B upwards We have v1=v2 for:

Accepted Answer

Each case

Answer

Case I

Answer

Case II

Answer

Case III

Question 7

Water is moving with a speed of 5.18 ms-1 through a pipe with a cross- sectional area of 4.20 cm3 The water gradually descends 9.66 m as the pipe increase in area to 7.60 cm3 The speed of flow at the lower level is:

Accepted Answer

2.86 ms-1

Answer

3.0 ms-1

Answer

3.82 ms-1

Answer

5.7 ms-1

Question 8

The velocity of kerosene oil in a horizontal pipe is 5 m/s. If g = 10m/s then the height head of oil will be:

Accepted Answer

1.25 m

Answer

12.5 m

Answer

0.125 m

Answer

125 m

Question 9

A manometer connected to a closed tap reads 3.5 x 10^5 N/m2 When the valve is opened, the reading of manometer falls to 3.0 x 10^5 N/m2, then velocity of flow of water is

Accepted Answer

10 m/s

Answer

100 m/s

Answer

1 m/s

Answer

10√10m

Question 10

Air is streaming past a horizontal air plane wing such that its speed in 120 m/s over the upper surface and 90 m/s at the lower surface. If the density of air is 1.3 kg per metre3 and the wing is 10 m long and has an average width of 2m, then the difference of the pressure on the two sides of the wing of :

Accepted Answer

4095.0 Pascal

Answer

409.50 Pascal

Answer

40.950 Pascal

Answer

4.0950 Pascal

Question 11

A cylinder of height 20 m is completely filled with water. The velocity of efflux of water (in m/s) through a small hole on the side wall of the cylinder near its bottom is:

Accepted Answer

20

Answer

10

Answer

25.5

Answer

5

Question 12

There is a hole in the bottom of tank having water. If total pressure at bottom is 3 atm (1 atm 105N/m2) then the velocity of water flowing from hole is:

Accepted Answer

20 m/s

Answer

10 m/s

Answer

30 m/s

Answer

None

Question 13

There is a hole of area A at the bottom of cylindrical vessel. Water is filled up to a height 'h' and water flows out in 't' second if water is filled to a height 4h, it will flow out in time equal to

Accepted Answer

2t

Answer

t

Answer

4t

Answer

t/4

Question 14

A cylindrical tank has a hole of 1 cm2 in its bottom. If the water is allowed to flow into the tank from a tube above it at the rate of 70 cm3/sec then the maximum height up to which water can rise in the tank is:

Accepted Answer

2.5 cm

Answer

5 cm

Answer

10 cm

Answer

0.25 cm

Question 15

A square plate of 0.1 m side moves parallel to a second plate with a velocity of 0.1 m/s, both plates being immersed in water. If the viscous force is 0.002 N and the coefficient of viscosity is 0.01 poise distance between the plates in m is

Accepted Answer

0.0005

Answer

0.1

Answer

0.05

Answer

0.005

Question 16

Two drops of the same radius are falling through air with a steady velocity of 5 cm per sec. If the two drops coalesce the terminal velocity would be

Accepted Answer

7.94 cm/s

Answer

10 cm/s

Answer

2.5 cm/s

Answer

5 x √2 cm/s

Question 17

An application of Bernoulli's equation for fluid flow is found in

Accepted Answer

Dynamic lift of an aeroplane

Answer

Viscosity meter

Answer

Capillary rise

Answer

Hydraulic press

Question 18

At what speed the velocity head at a stream of water be equal to 40 cm?

Accepted Answer

282.8 cm/sec

Answer

432.6 cm/sec

Answer

632.6 cm/sec

Answer

832.6 cm/sec

Question 19

The weight of an aero plane flying is balanced by

Accepted Answer

Force due to the pressure difference between the upper and lower surfaces of the wings, created by different air speeds

Answer

Upthrust of the air, which is equal to the weight of the air having the same volume as the plane

Answer

Vertical component of the thrust created by air currents striking the surface of the wings

Answer

Force due to the reaction of gases ejected by the revolving propeller

Question 20

Velocity of water in a river is

Accepted Answer

More in the middle and less near its banks

Answer

Same everywhere

Answer

Less in the middle and more near its banks

Answer

Increase from one bank to other bank

Free Fluid Dynamics MCQs with Answers