Question

Approximate the linear gas velocity in the trachea during normal exhalation. Do this by timing exhalations, measuring volumes of exhaled gas, and looking up or estimating the inner diameter of the trachea. A ballon or paper bag may be helpful to measure the volume of exhaled gas. Do more than one measurement and compute the average and standard deviation. Repete estimate for force exhalation. Describe the process that you used to make the calculations and estimites. List three potential sources of error.

Answer 1

let linear gas velocity in trachea be u

normal breathing rate = 20 breaths per minute

1 breath in 3 sec

hence, air is inhaled in 1.5 s

inner diameter of trachea, di = 0.02 m

volume of exhaled air = V

then

pi(di/2)^2*u = V/1.5

u = 8V/3*di^2*pi = 2122.0659*V

now from experiments, volume of air exhaled is

V (ml) = 510 489 502 481 498 512

Vav = 498.6666 ml

SD = 10.979779 ml

V = 498.66 +- 10.979 ml

hence

u = 1.0581 +- 0.023298 m/s

potential souirces of error

a. error in volume measurements of the air exhaled

b. error in time measurements for timiing breaths

c. under pressure performance may lead to abnormal results when comared to normal physiologicval condition