Mechanical Properties of Fluids

A plane is in level flight at constant speed and each of its two wings has an area of 40 m2. If the speed of the air is 180 km/h over the lower wing surface and 252 km/h over the upper wing surface, the mass of the plane is kg. (Take air density to be 1 kg m-3 and g = 10 m s-2)

A big drop is formed by coalescing 1000 small droplets of water. The surface energy will become :

1. 1100 th
2. 110 th
3. 100 times
4. 10 times

A small steel ball is dropped into a long cylinder containing glycerine. Which one of the following is the correct representation of the velocity time graph for the transit of the ball?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

A small spherical ball of radius r, falling through a viscous medium of negligible density has terminal velocity 'v'. Another ball of the same mass but of radius 2r, falling through the same viscous medium will have terminal velocity:

1. 4v
2. 2v
3. v4
4. v2

A big drop is formed by coalescing 1000 small identical drops of water. If E1 be the total surface energy of 1000 small drops of water and E2 be the surface energy of single big drop of water, then E1:E2 is x:1 where x= .

Given below are two statements: In the light of the above statements, choose the most appropriate from the options given below

1. Both Statement I and Statement II are false
2. Both Statement I and Statement II are true
3. Statement I is true but Statement II is false
4. Statement I is false but Statement II is true

In a test experiment on a model aeroplane in wind tunnel, the flow speeds on the upper and lower surfaces of the wings are 70 ms-1 and 65 ms-1 respectively. If the wing area is 2 m2, the lift of the wing is N. (Given density of air =1.2 kg m-3)

A small liquid drop of radius R is divided into 27 identical liquid drops. If the surface tension is T, then the work done in the process will be:

1. 4 R2T
2. 8 R2T
3. 18 R2T
4. 3 R2T

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :

1. Statement I is correct but statement II is incorrect
2. Statement I is incorrect but Statement II is correct
3. Both Statement I and Statement II are incorrect
4. Both Statement I and Statement II are correct

The reading of pressure metre attached with a closed pipe is 4.5 104 N/m2. On opening the valve, water starts flowing and the reading of pressure metre falls to 2.0 104 N/m2. The velocity of water is found to be V m/s. The value of V is .