An Evaporative Cooling Unit Needs to Pump 100 Litres of Air

question 31

Multiple Choice

An evaporative cooling unit needs to pump 100 litres of air per second through a pipe of radius 10 cm and length 10 m. How much of a pressure difference must be applied to the air to produce this flow rate? The viscosity of air is 1.8x10-5 Pa s.

• A) 4.6x10-9 Pa
• B) 1.44 Pa
• C) 0.46 Pa
• D) 460 Pa
• E) 0.057 Pa
• ANS

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