This looks like something out of a video game, but it’s for real. Some parkour masters can scale a building by jumping back and forth between two facing vertical surfaces, zigzagging upward. Seriously, check it out right now, I’ll wait. (It’s the move that starts at 0:10 in the clip.)
I’m not about to attempt this, because my job as a physics professor would be in jeopardy if I fell on my head. But from the safety of my office chair, I can walk you through how it works, because parkour is all about using physics to your advantage.
Use the Force, Luke
Friction is your friend here. When two surfaces are