Eight equal drops of water are falling through air with a steady terminal speed of 10 cm/s. If the drops coalesce, the new terminal velocity is:

An aeroplane of mass 4.5 × 104 kg and a total wing area of 600 m2 is travelling in horizontal flight at a constant height. The average pressure difference between the upper and lower surfaces of its wings is: (Take acceleration due to gravity g = 10 m/s2)

The surface tension of a soap solution is 2.0 × 10-2 N m-1. The work done to increase the radius of a soap bubble from 3.5 cm to 7.0 cm is: [Take π = 227]