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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Definitions:

Parietal Bone

A bone forming the central side and upper back part of each side of the skull.

Temporal Bone

A complex bone located at the sides and base of the skull, housing the structures of the ear and forming part of the side walls of the skull.

Frontal Bone

The bone forming the front part of the skull and the upper part of the eye sockets.