Why do some things float and others sink in water?
Duck vs. Coin
Why do some things float and others sink in water?
Drop a rubber duck in the bathtub and it bobs along, smug as anything. Drop a coin in beside it and — bloop — straight to the bottom. Both are small. Both are wet. So why does one ride the waves while the other gives up immediately? Let's find out.
Here's the secret nobody tells you: water doesn't just sit there politely. When you push something into it, the water pushes back, shoving upward on the object. This upward shove has a name — buoyancy. Everything you dunk gets the shove. The only question is whether the shove is strong enough.
