Cut a Rope With Itself

So you find yourself in a situation where you need to cut a rope, but you don't have anything to cut it with. When would this ever happen?  I don't know, but that's not the point. The point is, if you ever are in a situation where you need to cut a rope, you can impress everyone with this little trick. 

Step on one end of the rope, leave some slack and step on the rope with your other foot.  Then loop the rope through the slack and pull up. 

Start sawing back and forth and, depending on how thick your rope is, in a minute or two you will have caused enough friction to "saw" the rope.

The rope is suppose to be cut on the slack part where you were sawing back and forth.  This picture shows how successful we were with that. Only one strand of the rope was cut.

We cut the rope with the part that we were sawing with.  Not sure how it worked this way so we tried other types of rope, aka yarn, and the same thing happened.  Either way, we ended up with two pieces. The only problem is if it cuts with the sawing part of the rope you can't measure how long your two pieces will be.