I had a personal brush with Feynman with regards to this experiment.
Circa 1986, I read Surely You're Joking, Mr. Feynman and became mildly obsessed with the fact that Feynman doesn't present the result of the sprinkler experiment (see the first few seconds of the video for context). A number of colleagues (at the software startup where I was working) and I tied ourselves up in knots debating what the answer must be.
I wanted to perform the experiment, but lacking materials, skill, and (frankly) ambition, I settled for a laughably primitive apparatus involving a couple of bendy straws, the bathroom sink, and my mouth. This was enough to reproduce the well-known fact that if you push water out through the sprinkler, it will spin. When I tried sucking water in, it would give a momentary rotational jerk and then stop moving... but perhaps that was due to my mouth tightening up on the straw?!?
After I shared this inconclusive result, one of my co-workers decided to get to the bottom of the matter. He called the Pasadena operator, asked for the home phone of a Mr. Richard Feynman, and – to my utter horror – dialed the number.
It seemed impossible that this was a viable procedure for making contact with a Nobel Prize-winning physicist, but through the speakerphone, we could all hear a gruff voice that certainly sounded like it might be him. All doubt was removed when my friend explained that we were looking for the answer that isn't presented in the book, and the gruff voice said, "Why should I tell you?"
Feynman then asked whether we had tried the experiment, and to my redoubled horror, the phone was handed to me. I stumbled through some explanation of what I had tried and what result I had observed. Fenyman then relented, and explained the entire situation in ten short words:
"The sprinkler cannot rotate, because no angular momentum is transferred."
(Not an exact quote, but something very much like that)
That's basically saying that it's sucking air from all directions, not predominantly from the direction the pipe is facing. Counterintuitive to say the least.
My understanding here is shallow, but I think you are correct.
Here's a simple exercise to help your intuition: open your hand up flat, and hold it facing your mouth, a few inches away. Blow, and you can easily feel the air pressing on your palm. Now inhale sharply; your hand will feel no suction at all.
That's true, but all the air molecules entering a tube aligned with X axis have negative momentum along X. You'd think this means the total X momentum of all molecules become more positive.
Circa 1986, I read Surely You're Joking, Mr. Feynman and became mildly obsessed with the fact that Feynman doesn't present the result of the sprinkler experiment (see the first few seconds of the video for context). A number of colleagues (at the software startup where I was working) and I tied ourselves up in knots debating what the answer must be.
I wanted to perform the experiment, but lacking materials, skill, and (frankly) ambition, I settled for a laughably primitive apparatus involving a couple of bendy straws, the bathroom sink, and my mouth. This was enough to reproduce the well-known fact that if you push water out through the sprinkler, it will spin. When I tried sucking water in, it would give a momentary rotational jerk and then stop moving... but perhaps that was due to my mouth tightening up on the straw?!?
After I shared this inconclusive result, one of my co-workers decided to get to the bottom of the matter. He called the Pasadena operator, asked for the home phone of a Mr. Richard Feynman, and – to my utter horror – dialed the number.
It seemed impossible that this was a viable procedure for making contact with a Nobel Prize-winning physicist, but through the speakerphone, we could all hear a gruff voice that certainly sounded like it might be him. All doubt was removed when my friend explained that we were looking for the answer that isn't presented in the book, and the gruff voice said, "Why should I tell you?"
Feynman then asked whether we had tried the experiment, and to my redoubled horror, the phone was handed to me. I stumbled through some explanation of what I had tried and what result I had observed. Fenyman then relented, and explained the entire situation in ten short words:
"The sprinkler cannot rotate, because no angular momentum is transferred."
(Not an exact quote, but something very much like that)