Transcript:

If I am standing and I am holding a rope, what is the maximum effort I can put on the rope? It is simply the normal reaction of the ground to my weight multiplied by the coefficient of friction, whatever that number is.

And if I tell you that I can use this coefficient of friction so that even a 62 kg person like me can simply stand and hold in place an entire cruise ship and prevent it from moving, you will say, "Hey, you are crazy." But I can do it. What I can do is I can take a rope that is strong enough, and I can wrap it around a post, and then the other end of the rope I tie it to the cruise ship. And if the rope is strong enough and if I can wrap it enough times around the circle, using the Capstan equation, I can generate enough holding force like this.

It all depends on how many times the rope goes around the post, and the exponential makes it a huge multiplier. The effort is multiplied by an exponential quantity to generate a holding force which can be large enough. It's amazing.

This is how ships are held onto docks.