Submarine Science: STEM Activity

Submarine operates using the Archimedes' principle by manipulating the buoyancy. Let's perform a simple activity to understand its operation.

1. Plastic bottle
2. Glue gun
3. Screwdriver
4. Some Weights(You may use steel washers, nuts or castor wheel)
5. Candle and matchbox
6. 2 feet rubber tubing
7. Water tub

• Light up a candle and heat up the end of the screwdriver.
• Push the heated screwdriver through the bottle and poke 3 holes in it. Also, poke a hole through the cap on the bottle.
• Pass the rubber tubing through the bottle cap and water-tight it using a glue gun. Place the cap back to the bottle.
• Glue the weights near the holes using a glue gun.

Our Submarine is now ready to dive!

Place the bottle in a water tub. The bottle will float.

Now suck through the open end of plastic tubing. The bottle will start sinking slowly.

Next, blow air into the bottle. What will happen? The bottle will start coming to the surface just like a submarine.

So before dive into behind it, let's find out that what is Archimedes' principle.

“Archimedes’ principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is proportional to the weight of the fluid that the body displaces.”

Using the Archimedes principles, the buoyancy is controlled on the submarine by ballast tanks. These ballast tanks act similar to the bottle in our experiment. Submarines are less dense than water and hence they will float on seawater. In this condition, the ballast tanks are full of air. In order to submerge the submarine, it should be made less dense than water. This is done by venting out the air from the ballast tank and filling it with seawater in the process. The depth of the submarine is controlled by controlling the ratio of water to air in the ballast tank.