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Scuba Diving

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Suppose a balloon filled with air was released from the sea bottom. How does the surrounding pressure change as the balloon rises? What is likely to happen to the balloon before it reaches the surface? Explain.2. The bends is a life-threatening illness that results from too rapid a return to surface air pressure. During ascent, nitrogen dissolved in the blood stream comes out of solution as lung bubbles that can block the flow of blood to critical body organs. When construction of underwater foundations for the Brooklyn Bridge was underway, laborers worked in pressurized chambers. Upon a rapid return to the surface, many suffered from the bends. If you were in charge of this construction project, how might you protect these workers from decompression sickness? UPS AND DOWNS OF DIVING - SCUBA DIVING: Student Activity Create a Cartesian diver and watch what happens when you put it under pressure. Imagine entering a freshwater pond or lake. Take a deep breath and you're likely to float. Exhale, and you'll probably find yourself sinking. These "ups and downs" depend upon the amount of air in your lungs. As the volume of this gas increases, you become more buoyant. As the gas volume drops, you lose buoyancy and begin to sink. In this main activity, you'll construct a device called a Cartesian diver. Like a floating person, this diver has a buoyancy that depends upon its volume of trapped air. As you explore its behavior, you'll uncover the relationship between pressure and volume. Materials plastic 1- or 2-liter soda container with a screw-on lid, glass medicine drop. 1. Fill the container with tap water. 2. Lower the medicine dropper into the container. Squeeze the bulb slightly so that the glass tube becomes partially filled with water. 3. Set the dropper floating within the container. Add more water to the container so that the level of water rises to the brim. 4. Screw on the container lid. The seal should be tight enough to prevent the leakage of water. 5. Squeeze the center of the plastic container. What happens to the medicine dropper? Release your pressure. What happens now? Note: If the dropper remains afloat, you'll need to open the container and fill the dropper tube with more water. 6. Take a close look at the air bubble trapped within the medicine dropper. What happens to the bubble's volume as you squeeze the container? Can you explain the connection between this change in volume and the behavior of the medicine dropper? What happens to the bubble's volume when you release your grip? How does a change in volume relate to the movement of the medicine dropper? Extend the activity - Can you modify the design of your medicine dropper so that it can recover items that are scattered at the bottom of the container? First, design a diver that can retrieve paper clips and other objects attracted to magnets. Then, redesign your diver to "recover" targets that have eyelet-like handles. Is it possible to make a Cartesian diver out of other materials, such as the plastic cap to a pen, weighted with a bit of clay? See what objects will work. Questions1. Does squeezing the bottle force more water into the air or compress the air, making the diver heavier and causing it to sink? 2. How do these demonstrations relate to scuba diving equipment? How do they explain free divers' use of stones for weight as they dive?

Vocabulary

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Scuba Diving TRY ITS