A patient with asthma can experience a constriction of their airways. During a bronchospasm, their airway radius reduces from r=3mm to r=2.5 mm. What is the associated reduction in air flow rate if the change in pressure (ΔP) and length of the tube (L) are 125 Pa and 100mm respectively? Notes: apparent viscosity of air is 1.81x10^-5 Pa·s and flow rate (Q) is given by Poiseuille’s Law Q=(ΔPπr^4)/8ηL)
Fluid Pressure
The term fluid pressure is coined as, the measurement of the force per unit area of a given surface of a closed container. It is a branch of physics that helps to study the properties of fluid under various conditions of force.
Gauge Pressure
Pressure is the physical force acting per unit area on a body; the applied force is perpendicular to the surface of the object per unit area. The air around us at sea level exerts a pressure (atmospheric pressure) of about 14.7 psi but this doesn’t seem to bother anyone as the bodily fluids are constantly pushing outwards with the same force but if one swims down into the ocean a few feet below the surface one can notice the difference, there is increased pressure on the eardrum, this is due to an increase in hydrostatic pressure.
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