Science Experiment for Pressure Affecting Buoyancy

Hi, I'm Sean Tvelia, and we're here at Suffolk County Community College and today we're going to do an experiment to investigate pressure and buoyancy. Pressure is the force per unit area acting on a surface. To investigate how that affects buoyancy, well buoyancy occurs as a result of different densities. So whenever we have a material of lower density, it will be buoyant in a material of higher density. So to see how pressure can influence that I have produced a simple experiment that mimics a submarine using a liter bottle of water, a balloon and a simple air pump. What we will do is use the air pump to fill the balloon. As air moves into the balloon, the pressure inside the balloon will increase and as it overcomes the pressure of the water around it, the balloon will begin to expand and displace the water within the 1 liter bottle. As the balloon expands the density of the bottle will become less as more water leaves the bottle and the air goes in. As soon as the density of the bottle is less than the surrounding water, it will become buoyant and will float to the surface just like a submarine.