Norwegian physicist, Andreas Wahl tied himself to the side of a building 45 feet off the ground in an effort to demonstrate a basic law of physics.
The only thing keeping him from falling and potentially breaking a body part, or several, was a cable with a weight attached to the end.
At first, the weight was secured to the building.
But then a few of Wahl’s colleagues released the weight and Wahl immediately began to plummet to the ground:
While Wahl’s experiment seems risky, he’s actually perfectly safe. And that’s all thanks to a fundamental property of physics called centripetal force.
When Wahl’s colleagues released the weight, both he and it started to fall. Wahl fell straight under the force of gravity, but the weight — because it was placed at a distance from Wahl — traced an arc through the air, just like a swinging pendulum.
This force acting on the weight, centripetal force — the force that makes a body follow a curved path – was first described by Isaac Newton in the 17th century. And in this case, the force was the tension in the cable.
As the force of gravity pulled the weight down, tension from the cable pulled it toward a central point — the pipe. This induced an arc, which you can see below:
The weight continued to swing through the air, wrapping itself around the pipe.
After a couple of turns, the cable has wrapped around the pipe enough to stop Wahl’s fall just a few feet above the ground.
Because the friction between the cable and the pipe — as well as the cable’s elasticity — gradually slow Wahl’s motion as he drops, this reduces the jerk he felt when he comes to a halt. If he had stopped suddenly, he might have seriously injured himself.
Therefore, don’t try this at home. Leave this sort of thing to the physicists.
If you like, you can watch the full video here.