The Scuba Dive Experiment

The purpose of this project was to understand how the pressure of a scuba tank works at diffrent depths. We took the knowledge that we knew and created an experiment around it. We created this experiment using household objects such as two spherical balloons, measuring tape, brown lunch bags, stopwatch, and a bicycle.

Procedure:

1. Find the volume of the spherical balloon. We each took one breath and blew into the balloon, and tied the balloon end off so the balloon holds our air. Katie then measured the balloons using centimeters, and then gave Shelby the measurements to find the voulme of the spherical balloon. To find the volume of a sphere is V=4/3 (pi) radius cubed.

Katie measured Shelby breathing at rest, while jogging, and biking and vise versa for one minute each. We then multiplied our calculations by thirty, which gave us the total breaths for thirty minutes. We performed this experiment twice. We used a paper bag to let the counter be able clearly identify the number of breaths. We then multiplied the number of breaths for thirty minutes by the volume of each of our balloons. It is shown in these tables below.


We concluded that the average breathing would be 115 liters for thirty minutes. We chose to measure our breaths at rest, jogging, and biking because these excersises simulate underwater activity. There will be points in underwater activity where the diver will be at rest, swimming, and swimming strenously. The reason why we have a stretch with a warm up is because your not going to go diving without some type of preperation. Also this was to bring our breathing rate up to a constant level so that our breath outtake would be constant instead of erratic.

3. Calculate our results (Shelby answered)

Our total breathing is 115 liters for thirty minutes, and our scuba tank is cylindrical with measurements of 8 inches for diameter with a height of 26 inches. To calculate a cylinder we used the volume equation (pi) radius squared times height.

Volume of tank

8 in = 20.3 cm-diameter, 10.2 cm radius

26 in = 66.0 cm- height

V=(pi) 10.2 cm squared times 66.0 cm

V=21.6 L

Boyle's law where pressure inversly relates to volume to calculate pressure in the tank

V1=115 L

V2= 21.6 L

P1=2.0 atm

P2=? atm

(115)(2.0)=(21.6)(x)

x=11 atm

We calculate this at ten meters underwater, where there will be 2 atm's upon you. (at sea level there is one atm, and every ten meters underwater you go you will add one atm, so at ten meters underwater there will be 2 atm's) We created a chart to show the pressure at diffrent meters as well as the pressure in the tank at the different meters. Also the chart shows the intake of air one must take at different depths. This is important due to the distribution of different gases, and how much is taken in at different depths.

4.
calculations (Katie answered)

we calculated our breaths on land we must calculate them to be underwater. We did this by using Boyle's law shown below.

V1 115 L

V2 ? L

P1 1.o atm

P2 2.0 atm

(115)(1.0)=(x)(2.0)

x=57.5 L

The reason why the second volume of air would be half of the air on land is because when you go deeper your lungs have to double the intake making the volume reduce.

5. It is important to consider the temperature of the dive site because in colder water your air would compress in the tank while in warmer water your air would expand. Also in colder water your breath intake will be quicker. Diving off of the coast of Maine and then off of the coast of Florida would yeild different results. The warm water in Florida would have and expanding effect upon the tank, while in Maine the colder water would compress the tank. Also cold water has harsher conditions than warmer water in the fact that colder water is harder to breathe in, your body has to be active to stay warm, and it is ususally darker underwater. All of the have to be taken in to consideration for your dive to be successful wherever you may be. (Shelby answered)

6. To compress 3750 L of air into a 26 L tank you must use Boyle's law. (Katie answered)

P1 1.0 atm

P2 ? atm

V1 3750 L

V2 26 L

(1.0)(3750)=(x)(26)
x=140 atm

Since you are compressing so much air into such a small tank you will have a lot of pressure upon the tank.

7. Pressurized tanks are used so that the diver will have an adequate amount of air to breathe. The deeper underwater you go the more air that you need to breath, and if your tank is not pressurized then you won't have enough air to breath in at those depths. Your lungs are at risk of collapsing the deeper you go if your tank is not pressurized, so pressurized tanks allow deeper depths. (Both answered)

8. An overfilled scuba tank sitting out on a hot, sunny day is very dangerous for many reasons. The main reason being that hot air expands due to the fact that gas particles move faster when temperature increases. The gas particles will be hitting the insides of the tank so much harder and faster due to the temperature causing the tank to explode if not kept in reasonsable temperatures. You can think of this like 5 year olds being let out on the first day of summer vacation, but enclosing them in a small area. The children will bounce from one corner to the next because they want to play since it is nice and hot outside. (Katie answered)

9. If a cabin of a plane suddenly becomes depressurized at 30,000 feet the people on board will feel a sudden loss of air leading to uncounsciousness. This would happen because the plane was held at a chamber of depressurized air that would allow the people to breathe at such heights, and when this air is taken away its basically cutting of air supply to passangers. This would occur when there is a sudden depressurization, but if a bullet hit the plane then the results would be different. The difference in the two is that with the bullet there is only a small depressurization allowing breathing, but with sudden depressurization the product isn't as good. (Shelby answered)