Lung Capacity Lab

written by: Nancy Mims

Skills Used:

Working with formulas to solve problems
Determining the radius of a circle given the circumference
Calculating the volume of a sphere
Averaging data
Comparing theoretical and experimental results
Writing a Conclusion


Cloth tape measure
12 inch round balloons


1. Stretch the balloon by blowing it up several times.

2. Inhale as much air as possible and exhale the air into the balloon. Work hard
to empty your lungs completely.

3. Have another student measure (in centimeters) the circumference of the
balloon. Make sure the balloon is round and the measurement is from the
largest region.

4. Record the circumference

5. Repeat the procedure four times.

6. Calculate the average circumference from the five trials.

7. Using the average circumference and the formula for finding circumference,
compute the average radius of the sphere (your balloon).

8. Calculate the volume of the sphere.

9. Assuming 1cc of air = 1 ml of air, the volume of the sphere is your
experimental lung capacity.

10. Compute your theoretical lung capacity using the formula given below.

V = 0.041 h - 0.018 a - 2.69

where V is vital lung capacity in liters
h is your height in centimeters
a is your age in years

11. Compare the theoretical lung capacity to the experimental lung capacity.
Write a paragraph, on your own paper, explaining the comparison.