Posted by : Dr. Keyur Patel Thursday, 15 August 2013



Investigate how submarines dive and surface by changing their buoyancy in the water.

The first thing you need to do is cut 2/3 small holes out in the bottom of your sub. Then tape 4 or 5 heavy coins/ washers to either end. This will add weight to the craft and keep the holes facing the bottom. The next thing we need to do is attach a straw to the bottle top with clay. Place the short end of the flexible straw in the bottle and then take your clay and mold it all around the top of the bottle and the straw. Make sure there are no gaps for water to get in.  To allow the sub to deep dive, add a length of plastic tubing to the end of the straw.


Once launched, the submarine will start to sink as water floods through the holes along the bottom.  Keep the end of the plastic tube above the waterline at all times. Blow through the tube to fill the submarine with air. It will start to rise as the water gets blown out. With practice you will be able to make the submarine float at any depth you wish.


 

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