Source: NOVA: "Secrets of Lost Empires II: Medieval Siege" This media asset was adapted from NOVA: "Secrets of Lost Empires II: Medieval Siege" In medieval times, one of the most fearsome weapons was ...

Friction is an intrinsic physical phenomenon to curling. Without it, objects in motion would move endlessly, without slowing down. This would cause many safety-related problems: Cars or trains could ...

Oh, sure, you’ve seen a watermelon dropped from a balcony onto a trampoline. But what happens when you drop a car from a high tower onto a trampoline? That’s a whole new level of physics fun, and it’s ...

Michael Kanellos is editor at large at CNET News.com, where he covers hardware, research and development, start-ups and the tech industry overseas. You can store energy in chemical batteries.