The tangential velocity of the water element having a free vortex is
A. Directly proportional to its distance from the centre
B. Inversely proportional to its distance from the centre
C. Directly proportional to its (distance)2 from the centre
D. Inversely proportional to its (distance)2 from the centre
Answer: Option B
In free vortex (irrotational flow - circulation is zero along closed contour) tangential velocity is inversely proportion to distance from center.
In forced vortex (rotational flow - circulation is zero along closed contour, leave dropped will rotate) tangential velocity is directly proportion to distance from center.