How To Make A Submarine

Step 1: You Will Need

Step 2: Aim

The aim of this experiment is to demonstrate the principle of buoyancy

Step 3: Method

Drop each sachet into the pint glass full of water. Use the one that floats between the other two.
Take the bottle full of water and put in the chosen sachet, be careful it doesn't split!
The bottle must be completely filled for the experiment to work. Screw the lid on tightly
Now squeeze the bottle. The sachet will dive to the bottom of the bottle. Now let go and swim back to the top again. Squeezing it harder. makes it dives even faster.

Step 4: Conclusion

This experiment demonstrated the principle of buoyancy, which is that if the water that is displaced or 'pushed aside' by an object weighs more than that object, then it will float. If it weighs less than the object then it will sink.

When the bottle is squeezed, it applied extra pressure to the air bubble inside the diver, which reduced the size of that air bubble. And as the bubble got smaller, the diver became less buoyant and began to sink.

Fish use this method to enable them to sink or float. They have a small air sac in their bodies, and use their muscles to squeeze or relax this sac. And submarines can be made to rise and sink using the same principle, by pumping water in and out of tanks onboard..

Experiment Complete!