Submarine Buoyancy Vanderbilt Student Volunteers for Science Fall, 2005 Training Presentation

Important! Please use this resource to reinforce your understanding of the lesson! Make sure you have read and understand the entire lesson prior to picking up the kit! We recommend that you work through the kit with your team prior to going into the classroom. This presentation does not contain the entire lesson—only selected experiments that may be difficult to visualize and/or understand.

I. Introduction (p. 2) Float vs. sink Definition of “density” Use large Cartesian diver to demonstrate principles of density Squeezing the bottle causes the volume to change and affect the density of the bulb

II. Building the Submarine (p. 3) Pass out soda bottoms ¾-filled w/water, pie pan and empty canisters (no pennies yet) What happens to the canister when placed in the water? What if water is added to the canister? (In both cases, it floats.)

II. Building the Submarine (p. 3) Pass out container w/15 pennies to each group. Students begin w/10 pennies in the canister—add one until the canister sinks. Retrieve the canister with the fish net. Remove one penny. –This is extremely important—there must be one less penny than the number it takes to sink the canister. The activity will not work if this step is not followed.

III. Demonstration (p. 4) What can you do to make an object that has sunk, rise again? Pour citric acid solution into clear cup. Add a spoonful of baking powder and observe. The fizz will be the “fuel” that will allow the submarine to rise. As more gas is produced, a gas bubble is formed that increases in size. As it grows, it pushes more water out of the canister, reducing the mass of the canister. The gas does NOT propel the canister upwards!

IV. Raising the Submarine (p.5) Pass out 1 citric acid bottle, 1 baking powder container and 1 taster spoon to each group. Put the appropriate number of pennies into the canister (see slide 5). Fill the canister about ¾ full with citric acid. While one student holds the canister and lid over the bottle, another should add 1 spoonful of baking powder to the canister. Quickly seal the lid and drop the canister LID DOWN into the bottle.

IV. Raising the Submarine (p.5) If nothing happens after a minute, remove the film canister. –Rinse the pennies. –Dry the pennies, the canister and the lid. Repeat the experiment using 8% NaCl solution in the beaker. Students may need to add another penny or two to sink the canister.

V. Summary and Discussion Two factors affect density: mass and volume. Pipette bulb diver: example of changing volume Film canister submarine: example of changing mass