Filtered Air Is Pumped Down a Tube of Diameter 50

Multiple Choice

Filtered air is pumped down a tube of diameter 50 cm into a hospital operating theatre. The idea is that a laminar flow over the patient will prevent contamination. What is the maximum safe speed at which the air can be pumped which will ensure that the flow is not turbulent? The density of air is 1.2 kg m-3 and its viscosity is 1.8x10-5 Pa s.

A) 1.2 cm s-1.
B) 3.4 cm s-1.
C) 6.9 cm s-1.
D) 12.0 cm s-1.
E) 23.4 cm s-1.ANS