Labs 2-3 Calculating the Volume of a Breath

Tidal breathing is normal, resting breathing. The tidal volume is defined as the volume of air that is

inhaled or exhaled in only a single such breath.

The average human respiratory rate is 30-60 breaths per minute at birth, decreasing to 12-20

breaths per minute in adults.

Materials needed:

12" Round Balloons 2 packs of 10 will be sufficient (Can get them in a dollar store)

A tape measure with cm markings (unless you want to convert inches to cm)

A ruler

Watch, clock, or stopwatch

Yourself and 3 volunteers: different ages but teenage or older

different heights

female and/or male

Note: Enter all your data in the Excel spreadsheet provided.

Procedure:

Respiration rate of your normal resting breathing

Count the number of breaths you take in one minute.

• Blowing up the balloon:

Take a deep breath and blow into the first balloon.

Repeat four more times in the same balloon.

Seal the balloon.

Repeat for a total of 3 balloons.

.

Perform procedures 2 and 3 with your 3 volunteers.

Measuring the volume of the balloon

It is difficult to measure the volume of the balloon directly so you will derive the volume based

on the geometry of a sphere.

To get r (the radius) wrap the tape measure around the widest part of the balloon to determine its

circumference. You can squeeze at the knot to make the balloon more spherical./n3

4

5

6

7

9

10

11

12

13

14

15

Since the circumference of a circle = 2 xr then r = circumference/2.rt

You can now plug the r into the equation of a sphere to determine the volume of the sphere.

Volume of sphere= Tr³

.

radius: r circumference/2x Volume of sphere (4/3)3

M

Balloon

Number Circumference

initials Paricipant F (years) (in) (cm) breaths/min breaths (cm)

Your

or Age Height Height Rate in

Respiratory

Balloon Balloon Balloon

Radius Volume Volume

(cm) in (cm)3 in liters

Volume per

Breath in liters

Average

Volume per

Breath in (cm)3

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