Question

Tests of lung capacity show that adults are able to exhale 1.3 liters of air through their mouths in as ittle as 2 seconds. blows air at this rate through a drinking straw with a diameter of 0.80 cm, what is the speed of air in the straw? n/s a second straw (b) Ir the air from the straw in part (a) is directed horizontally across (Take the density of air to be 1.29 kg/m) the upper end of a second straw that is vertical, as shown in the fgure, to what height does water rise in the vertical stra

Answer 1

Delta V/Delta t = AV = > v = Delta V/Delta t/(1/4 pi d^2) V = (1.3 times 10^-3/2)/(1/4 pi (0.006)^2) = 22.98 m/s (b) p_1 + 1/2 P v^2_1 = P_2 + 1/2 P V^2_2 P_2 - P_1 = Delta P = 1/2 P V^2_1 = 1/2 (1.29) (22.98)^2 Delta P = 340.61 Pa P_2 = P_1 + rho w h g h = P_2 - P_1/rho w g = Delta P/rho w g = 340.61/1000 times 9.81 h = 3.472 cm