### Fluid Mechanics

11. A model of a reservior is drained in 4 mts by opening the sluice gate. The model scale is 1: 225. How long should it take to empty the prototype ?

1. 900 minutes
2. 4 minutes
3. 4 x (225)3/2 minutes
4. 4 (225)1/3 minutes
5. 4 x V225 minutes.

4 x V225 minutes.

12. A model of torpedo is tested in a towing tank at a velocity of 25 m/sec. The prototype is expected to attain a velocity of 5 m/sec. What model scale has been used ?

1. 1 : 5
2. 1 : 2.5
3. 1 :25
4. 1:V5″
5. 1 : 53/2

1 : 5

13. A one dimensional flow is one which

1. is uniform flow
3. takes place in straight lines
4. involves zero transverse component of flow
5. takes place in one dimension.

involves zero transverse component of flow

14. A perfect gas

1. has constant viscosity
2. has zero viscosity
3. is in compressible
4. is of theoretical interest
5. none of the above.

none of the above.

15. A piece of metal of specific gravity 13.6 is placed in mercury of specific gravity 13.6, what fraction of it volume is under mercury?

1. the metal piece will simply float over the mercury
2. the metal piece will be immersed in mercury by half
3. whole of the metal piece will be immersed with its top surface just at mercury level
4. metal piece will sink to the bottom
5. none of the above.

whole of the metal piece will be immersed with its top surface just at mercury level

16. A piece of metal of specific gravity 7 floats in mercury of specific gravity 13.6. What fraction of its volume is under mercury ?

1. 0.5
2. 0.4
3. 0.515
4. 0.5
5. none of the above.

0.515

17. A piece of wood having weight 5 kg floats in water with 60% of its volume under the liquid. The specific gravity of wood is

1. 0.83
2. 0.6
3. 0.4
4. 0.3
5. none of the above.

0.6

18. A piece weighing 3 kg in air was found to weigh 2.5 kg when submerged in water. Its specific gravity is

1. 1
2. 5
3. 7
4. 6
5. none of the above.

6

19. A pressure of 25 m of head of water is equal to

1. 25 kN/m2
2. 245 kN/m2
3. 2500 kN/m2
4. 2.5kN/m2
5. 12.5 kN/m2.

245 kN/m2

20. A ship whose hull length is 100 m is to travel at 10 m/sec. For dynamic similarity, at what velocity should a 1:25 model be towed through water ?

1. 10 m/sec
2. 25 m/sec
3. 2 m/sec
4. 50 m/sec
5. 250 m/sec.