Physical Science Sunken Treasure Project*

What title will you choose? In the realm of ClassCraft, you must discover the treasure that is found in a sunken city *NOTE: If you are not participating in ClassCraft, feel free to name this SCUBA diving project You are given a special helmet that allows you to see underwater as well as a special backpack that allows you to breathe underwater for a short time The time depends on the person and the depth

Can’t hold your breath Your backpack holds the equivalent of 2200 L of air The average person breathes 1 L of air with each breath To determine how long your air will last, you must first determine how long it will last above water

How long will the air last To find out how many breathes you take each minute With a partner, breath normally for one minute and count the number of breathes you take Do this at least three times and take the average Multiply the average times 1 L This tells you the amount of air per minute that you would breathe

How long will the air last…you? Now you need to know how long the air would last ABOVE the water Divide the amount of air in the tank by YOUR air per minute. Example: A person breathes an average of 20 breathes per minute 20 x 1 = 20 L of air per minute 2200/ 20 = 110 minutes of air (above water)

Freshen up a bit Above the water, you have one atmosphere of pressure above you As you dive deeper, there is more and more water pressure adding to the air pressure The amount depends on the depth and the type of water In freshwater, every 33 feet of depth equals 1 atm of air If you dive 33 feet, there is 1 atm of water and 1 atm of air = 2 atm If you dive 66 feet, there is 2 atm of water and 1 atm of air = 3 atm In saltwater, the water is heavier (from the salt), so you don’t have to dive as deep to increase the pressure

(Not) in the salty air In saltwater, every 30 feet of depth equals 1 atm of air If you dive 30 feet, then there is 1 atm of water and 1 atm of air= 2 atm If you dive 60 feet, then there is 2 atm of water and 1 atm of air = 3 atm

How to determine how much pressure for a depth For any depth, to determine the amount of pressure Saltwater: depth/ Freshwater: depth/ This will be important later

Planning Factor The treasure is inside a sunken building inside a sunken city The city was near the sea when it slid it became submerged. That means, you should plan for a salt water dive

X Start Point TREASURE MAP

How long will it take you to swim? You determine that your swim speed is 25 feet per minute You must determine: How long you will spend at each depth How much air you will use at each depth It will take you 2 minutes to pick the lock on the treasure chest OR you can swim with the whole thing at ½ speed Next, you will need to know some measurements

X Start Point 20 feet 10 feet 30 feet 15 feet 60 feet Horizontal Distances

X Start Point 10 feet 5 feet 50 feet 10 feet 5 feet 20 feet 65 feet Vertical Distances

The Plan You must decide what route that you will take to get to the treasure Remember, you need to maximize your air supply, so I recommend swimming on the surface for as long as you can This will not take away from your air supply Break your dive into stages (0 ft depth, 10 ft depth, 20 ft depth, etc)

The Plan, continued Use your swim speed and the horizontal distances to determine how long you will spend at each depth When you dive down, use the swim speed again to see how long you will dive To be safe, use the deepest depth of that stage to figure out air usage Any difference will be on the way back up Speaking of, DON’T FORGET about swimming back to the start point!

What to turn in Take the map slide (slide #10) and sketch out your dive route Label the distance and time for each segment as well as overall time Show the breathing test that you did with your partner Number of breathes for each minute and the average number of breathes per minute The average amount of air per minute Fill out the data table

Data Table Stage Depth (ft) Distance (ft) Time (minutes) Pressure (atm) Air Used (L) Air Remaining (L) Calculation

Data Table Segment is for each swimming section that you do there AND back On my example it would appear that I would have 7 segments (3 down, 1 at the bottom, and 3 back up) However, as I travel through different depths, it would have to be broken up more ONCE AGAIN, use straight horizontal and vertical distances for easier math There is a section for Boyle’s Law calculations

Boyle’s Law calculation tips If you compare everything to the surface, it will be easier P 1 = 1 atm V 1 = 2200 L P 2 = Depends on the depth V 2 = this is what you will calculate Divide V 2 by your breathing rate to get the amount of air used.

Example sketch The following slide shows an example of a route that you could take I don’t recommend it You would be underwater longer You will use more air The math is more challenging (Pythagorean Theorem and all of that) Once again, I suggest that you use straight horizontal and vertical movements instead of diagonal ones

X Start Point 76 feet; 3.04 minutes 45 feet; 1.8 minutes 25 feet; 1 minute 2 minutes Total Time: minutes

WARNING Don’t forget that the deeper you go, the faster your air will be used At 60 feet, you are using air 3 times as fast as on the surface So, if you spend 2 minutes at the bottom, you will use more than 6 minutes of air Why more? Because it is deeper than 60 feet!

ClassCraft rewards For those of you NOT doing ClassCraft, this is a project grade For those of you who are participating in ClassCraft, it is STILL a project grade. In addition, the game rewards are: Up to 1050 XP (based on grade) Every point over a 70 yields 15 XP Up to 1000 GP (based on grade) I will take your percentage grade and multiply this number for your reward

Grading I will be checking your thought processes and ESPECIALLY your Boyle’s Law calculations Initial breathing calculations: 15% Copy of treasure map with labeled distances and times for each segment as well as overall time: 25% Completed data table with all calculations correct: 60%