It's difficult to look up in the sky during a clear day and not see at least one cloudy trail billowing from an airplane. Although they're officially called contrails, some people refer to them as "chemtrails" -- and have interesting explanations for their existence.
WHAT'S INSIDE: TRANSPORTATION
Inside an airport, luggage moves through an amazing and intricate system. The baggage handling system plays a crucial role in keeping travelers happy. Learn about these high-speed carts and conveyers.
A fascinating article that describes how a block and tackle (as well as levers and gears) works!