- If two astronauts are floating in space and one of them shoves the other, how come they both float away in opposite directions?
- What makes a car move forwards?
Walking is such a simple task that most mammals can do it mere hours after being born. (It takes humans a few years to figure it out, but we get there eventually.)
It’s so simple that the average person, unless they are a very special type of person, does not think very hard about the physics of walking.
But think about it: how does it really work? One leg moves forward, the other moves back, and somehow your entire body gets propelled in the direction you want to travel. It’s a great mystery!
Or perhaps you’re rolling your eyes right now. “Come on,” you’re saying, “don’t be an imbecile! Each time you move a leg backwards, you push yourself forwards at the same time. Easy!”