Experimenting with Buoyancy Buoyancy (boy-an-see) is the upward force that a liquid exerts on an object. If the downward force (weight) of the object is less than the buoyancy force on it, the object will float. Things that float are “positively buoyant.” Go to the next slide

Experimenting with Buoyancy If the weight of the object is greater than the buoyant force of the water on it the object will sink. Things that sink are “negatively buoyant.” If the buoyant force and the weight of the object are equal the object will hover in one place. Things like this are “neutrally buoyant.” Go to the next slide

Experimenting with Buoyancy Take the box out of your cabinet labeled “Cartesian Diver” Remove the top of the bottle Take the bottle to the sink and fill it with water, Be careful not to make a mess! Go To The Next Slide

Experimenting with Buoyancy Take the Pipette from the box Dip the tip of the Pipette in the top of the bottle and draw water ¾ of the way up the long part of the pipette by squeezing the bulb and letting it go Drop the Pipette into the bottle, but make sure it floats! Go To The Next Slide

Experimenting with Buoyancy If the Pipette is floating in the bottle, screw the cap on the bottle. If the Pipette sinks, you need to get it out and remove some water from it. Once the Pipette is floating in the bottle with the cap on, take a picture of the assembled experiment. Go to the next slide

Experimenting with Buoyancy With the top on, squeeze the sides of the bottle. What happens to the pipette inside the bottle? Record your observations. When you squeeze the bottle, what happens to the water level inside the pipette? Make sure you record your observations! Go to the next slide

Experimenting with Buoyancy Have someone take a picture of your experiment in three positions. Take a picture of the pipette floating at the top of the bottle. Take one of the pipette at the bottom. Try to get the pipette to float in the middle of the bottle. Take a picture of this as well. Go on to the next slide

Experimenting with Buoyancy Draw a line on the picture of the pipette where the water is when it is floating On the second picture, draw a line where the water level is when the pipette is at the bottom of the bottle What do you think is happening here? Write down your observations on the sheet. Go to the next slide

Experimenting with Buoyancy When the pressure increases in the bottle (when you squeeze it) the air in the pipette is forced to take up less volume. (space) When the air pocket gets too small to support the weight of the pipette, it sinks to the bottom of the bottle. Go to the next slide

Experimenting with Buoyancy Submarines sink or rise by controlling the amount of water in their variable ballast tanks. The diver that you made is just like a mini- submarine. Proceed to the next activity