Archimedes once famously said “give me a place to stand, and I shall move the Earth.” This wasn’t some bogus philosophical statement. The ancient physicist was just trying to illustrate a simple, but highly effective machine: the lever. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. Every lever consists of three main components: the effort arm, the resistance arm, and the fulcrum. TedED just released this fantastic video explaining how the lever works by illustrating one of its most common applications – the  teeter-totter, or seesaw. Remember these from when you were a kid? Sure you do. When a big-boned friend stepped on the other end, you would get stuck mid air. But if you moved back, you would tip the scale back. Effectively, you were using a lever to lift a heavier weight. This is how the Egyptians moved and lifted obelisks weighing more than 100 tons. No aliens, sorry. If you’d like to know how long a lever you’d need to move the Earth, check out the animation.

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