Buoyancy Question Here we have a toy submarine floating in a bathtub. It's a really fancy sub, made out of steel. The sub weighs one pound. When completely submerged, it displaces two pounds of water. What could you do to cause the sub to sink to the bottom of the tub? Add one pound of sand to the sub's interior. Add one pound of sand to the sub's interior, plus a little more. Nothing. Since the boat displaces more water than it weighs, it's already on its way down. Back to Buoyancy Brainteasers Stories in the Timber | Explore the Shipwreck | Who Owns Lost Ships? Buoyancy Brainteasers | Teacher's Guide | Resources | Transcript | Site Map Voyage of Doom Home Editor's Picks | Previous Sites | Join Us/E-mail | TV/Web Schedule About NOVA | Teachers | Site Map | Shop | Jobs | Search | To print PBS Online | NOVA Online | WGBH © | Updated November 2000