Imponderables(R): Science (Collins Gem)

Chapter One

Why Do Straws in Drinks Sometimes Sink and Sometimes Rise to the Surface?

The movement of the straw depends upon the liquid in the glass and the composition of the straw itself. The rapidly rising straw phenomenon is usually seen in glasses containing carbonated soft drinks. Reader Richard Williams, a meteorologist at the National Weather Service, explains the phenomenon:

...the rise occurs as carbon dioxide bubbles form on both the outside and inside of the straw. This increases the buoyancy of the straw and it gradually rises out of the liquid.

The gas is under considerable pressure when the drink is first drawn or poured. When that pressure is released the gas forms small bubbles on the sides of the glass and on the straw. As the bubbles grow the straw becomes buoyant enough to "float" higher and higher in the container.

Occasionally, though, a straw will rise in a noncarbonated beverage, and we didn't get a good explanation for this phenomenon until we heard from Roger W. Cappello, president of strawmaker Clear ... read full excerpt from: Imponderables(r): Science (Collins Gem) ebook