The most famous tunnel is the thirty mile "Chunnel" between England and France. The Chunnel is actually two separate tunnels, connected by cross passages.
When a train enters a tunnel, it compresses the air in front of it like a piston. Air in a tunnel can't be simply pushed aside--the tunnel walls are in the way.
Aw, the ticking of the hourglass. Ticking hourglass? Clocks tick. Hourglasses flow. Are we mixing our metaphors? Learn more on this Moment of Science.
What happens when a droplet of liquid lands on a glass surface?
Some very adventurous people have used big suction cups to climb the fronts of glass buildings. However, they’d better not climb too high, because the higher you go, the less effective a suction cup will be. In space they’re no good at all! Learn more on this Moment of Science.
It may seem that the Denver Nuggets have quite the advantage when playing the Detroit Pistons as a result of altitude. Learn more on this Moment of Science.
As your car rapidly decelerates, you feel yourself pushed up against the wheel. Why? Learn more on this Moment of Science.
What happens when a volcano erupts underwater? Find out on this Moment of Science.
Want to try a neat experiment that shows air pressure at work? "The Invisible Hand" on this Moment of Science.
What does air actually consist of? Find out on this Moment of Science.