Maritime Antiques and Collectibles

Submarine Full

by admin | October 21st, 2010

Submarine Full

A little science help in submarine physics?

OK, so hear me out... my science teacher gave us this assignment for bonus marks. He said we can use some plasticine (play-doh-like stuff) and a pen cap. Then we need to fill up a bottle with water. Somehow, when combined, the plasticine and pen cap will have the following results; when you squeeze the bottle of water, the cap (or submarine) will fall to the bottom of the bottle, and when you let go of the bottle the "submarine" rises back to the surface. Could someone guide me through how to make this happen, and explain the physics of it, (so I can receive full marks) ? Thanks!

Easy.

Put a little plasticine on the pocket clip so the cap floats open end down.

Now allow just enough water into the cap that it ALMOST sinks. That is the hard part. You want the cap as close as possible to sinking without sinking.

Fill the bottle completely full. Put your finger over the end of the cap and put it in the bottle. Be careful that you don't lose any water from the cap.. If so, start over.

Top the bottle off again. At this point the cap should be just floating, almost about to sink.

Seal the bottle with its lid and / or Plasticine. There must be no air bubbles in the bottle. If so, start over.

You are done.

Why it works. Believe it or not, the sides of the bottle are slightly Flexible (a rectangular base bottle works best). When you squeeze the bottle the sides flex in increasing the pressure in the water. That pushes water in to the pen cap. If the pen cap is almost sinking the extra water is enough to make it sink. Release the pressure on the bottle and the pressure in the water decreases water moves out of the pen cap and the cap floats.

Yellow Submarine Full Movie Part 1