Tests of lung capacity show that adults are able to exhale 1.3 liters of air thr

Question

Tests of lung capacity show that adults are able to exhale 1.3 liters of air through their mouths in as little as 2 seconds. (a) If a person blows air at this rate through a drinking straw with a diameter of 0.70 cm, what is the speed of air in the straw? m/s (b) If the air from the straw in part (a) is directed horizontally across the upper end of a second straw that is vertical, as shown in the figure, to what height does water rise in the vertical straw? (Take the density of air to be 1.29 kg/m3.) cm

Explanation / Answer

1.3 L= 1.3*10^-3 m^3

Rate of volume flow= 1.3*10^-3/2s= 0.65*10^-3 m^3/s

Area of straw= (0.7*10^-2)^2/4= 3.846*10^-5 m^2

Speed of air trough straw, s= volume per second/area= 0.65*10^-3/(3.846*10^-5)= 16.9 m/s

b) pressure drop = (rho)v^2/2= 1.29*(16.898)^2/2= 184.18 Pa

1 Pa= 0.010197 cm of water

184 Pa= 1.876 cm

Plz rate

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