How to Make Graduated Cylinders Float
- 1). Place air tubing all the way into graduated cylinder and tape in place. Be sure not to completely cover the opening into the graduated cylinder. Use a wire hanger to make a central loop to hold and guide the graduated cylinder. First, loosely loop wire around the graduated cylinder halfway along length of wire. Then, position the wire loop (holding the graduated cylinder open-end down) so cylinder cannot touch bottom of pail. Next, loop the wire ends to sides of the pail to support it and tape wire-ends to the pail to hold in place. Once everything is in position (with the graduated cylinder inside the wire loop with an air hose leading from inside the upturned graduated cylinder to outside the pail) fill pail with water.
- 2). Blow into the hose so that the air is transmitted from your lungs to the graduated cylinder which then begins to fill with air. This air 'displaces' the water making the 'buoyant force'. As the weight of the graduated cylinder is exceeded by the weight of the displaced water the buoyant force overcomes the downward force of gravity and rises. (You may have to adjust the wire loop so the graduated cylinder can move smoothly up and down.)
- 3). Inhale the air in the cylinder so that it is drawn into your lungs and water rises into the graduated cylinder to take the place of the departed air. As the volume of the air decreases the amount of water being displaced decreases and so does the buoyant force. The graduated cylinder sinks.
- 4). If you are using a clear pail or pitcher it is possible to weight the graduated cylinder using the following method: First, suck all the air out of the cylinder. Then, slowly add air until the graduated cylinder is just on the cusp of rising or just begins to rise. Next, pinch the air hose so air is held at that point. Read the graduated cylinder for how many cubic centimeters (cc) of air is now in graduated cylinder (this shows total amount of displaced water). Each cc of water is equal to one gram so multiply the total amount displaced (cc) by one gram to find total weight of graduated cylinder.
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