system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why doesn't Boyle's Self Flowing Flask work to power a generator?

I had a friend bring up Boyle's Self Flowing Flask  Generator idea to me and I having trouble explaining to him why this won't work, could use some help finding my words.

**Edit** Never mind, I was describing it in too general of terms and he was misunderstanding me. The terms output and input was throwing or conversation off.
gpt
First, the flask is an imaginary device. It does not exist. If you try to build one, it doesn't work right.

Second, any device that is designed to run on and on using its own momentum *only* works if you don't draw energy away from it. As soon as you draw energy away from it -- by requiring it to do work -- it quickly grinds to a halt.

For example, you can use a moving car to generate heat by friction, but very soon the car just stops and stays stopped! In fact that's how brakes work. Unfortunately even the smallest amount of friction -- like water rubbing against the inside of a pipe -- is enough to eventually stop anything, so no machine just runs forever without a push. And that gets *much worse* if you hook up a generator.