Schematic illustration of the picture of children playing teeter-totter.

Sinking Submarine

How Does a Submarine Float and Sink?

 

Materials

  • 2-liter soda bottle with cap
  • tub of tap water

Try This

  1. Place the soda bottle with the cap screwed on in the tub of tap water. What happens to the bottle?
  2. Remove the bottle from the water.
  3. Fill the bottle with water and screw the cap back on.
  4. Again, place the bottle in the tub of water. What happens now?
Schematic illustration of a soda bottle with cap and a tub of tap water.

What's Going On?

When you first put the bottle in the tub, it floated. After you filled the bottle with water, it sank to the bottom of the tub. A submarine uses air and water in special tanks, called ballast tanks, to move up and down in the water. To dive, the submarine's tanks are filled with water. To rise, the tanks are filled with compressed air, which pushes out the water. A combination of air and water allows the submarine to stay at different depths of water. Fish use a similar method to swim at different depths in the ocean.

Schematic illustration of a bottle floating on a tub of water.