Mechanical Properties of Fluids

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 .