How much flow and volume from urination do you need to levitate your whole body for two seconds off the floor?

[stinky@redlemmy.com]

what material would a bladder need to be made out of... hrm hold pls

[xmunk@sh.itjust.works]

Your urethra is going to be really fucking sore.

[andrewta@lemmy.world]

I question your statement of , it just falls out. If it only fell out you couldn’t piss any distance other then down. Yet you can get quite the distance. So there has to be some force there. Although it would be quite small

[fermion@feddit.nl]

You may need to double the flow. With the water powered jet packs the water isn't just being accelerated from a standstill. The water is first flowing up with close to the same speed and is redirected down. So the momentum exchange is twice what it would be if the water were stored in tanks with the flyer.

[scoobford@lemmy.zip]

So technically, you are correct. The force is the water pressure provided by the piss being pulled down by gravity. Practically speaking, this force is negligible because all you're doing is allowing the piss to fall, not forcing it downwards.

Basically, imagine you're holding an incredibly heavy rock that does not have a gravitational field or air resistance. If you drop the rock, gravity will pull it down, but regardless you will not go up unless you apply force and throw it down.

[honeymustardgas@lemmy.world]

Yea, I previously just learned that the psi depletes as soon as it leaves the contraption because there is much less pressure, and it is just speed coming out.

[honeymustardgas@lemmy.world]

That would be a challenge to find out. Because I would look for the material with the minimum durability, not just a metal tank, lol. Like what is the weakest material that can still withstand this type of thing.

[sbv@sh.itjust.works]

Flipped inside out, even.

[stinky@redlemmy.com]

Silicone Rubber

Polyurethane (PU) Elastomers

Thermoplastic Elastomers (TPEs)

or traditional latex rubber

[tokenboomer@lemmy.world]

Comments are locked. This question has been answered.

[jeinzi@discuss.tchncs.de]

Aerospace engineer here. To levitate, the force of the exhausted mass flow (F=ṁv) has to equal the pull of gravity (F=mg) on your body.
The gravity of earth is g=9.81N/kg. Wikipedia says the average body mass is 62kg. It also says the bladder capacity of an adult is about 400ml, and I'll assume the density to be 1kg/l. You want to levitate for 2 seconds, so your mass flow needs to be ṁ=0.4kg/2s=0.2kg/s.
If you rearrange the equation, you get v=mg/ṁ=62kg9.81N/kg/(0.2kg/s)=3041m/s.

So if you manage to pee with a velocity of about 3km/s, you can levitate for 2 seconds with an average sized bladder.

To achive that, your "exhaust" must be clenched to a diameter of about 0.29mm. This gives a cross-section of 0.66mm² or 6.6*10^-8m². Multiply that with the velocity of 3041m/s and you again get your flow of 0.2l/s.

Of course, during those 2 seconds you loose mass and therefore, earth's pull on you gets less and you start to accelerate. We can use the rocket equation to calculate your final velocity to 3041m/s*ln(62kg/61.6kg)=19.7m/s

You'll end up flying into the ceiling at about 71km/h and probably die. This could be avoided if you had very precise control over your bladder and would continously reduce your pee velocity.

[bradorsomething@ttrpg.network]

Will the density of my pee affect this?

[jeinzi@discuss.tchncs.de]

Yes, higher density means you exhaust more mass during those 2s, and therefore you don't have to pee so fast.

[ultragigagigantic@lemmy.ml]

Fuck yeah science

[ininewcrow@lemmy.ca]

Beautiful, I was waiting for an engineer to do the calculations .... so in layman's terms, clench your urethra, push your bladder as hard as unhumanly as possible and hope to everything that is holy that your entire urinary tract doesn't explode before your urine leaves your body.

[chuckleslord@lemmy.world]

It's not a question of if your urinary tract will explode, but where.

[ininewcrow@lemmy.ca]

I guess we'll have to keep experimenting to determine which parts need the reinforcing in order to achieve our goal of two second levitation

[crackhappy@lemmy.world]

frantically starts drinking heavy water

[iamanurd@midwest.social]

According to one of my favorite shorts of all time, the answer is “I don’t know”

[bradorsomething@ttrpg.network]

I remember learning a bladder begins to spasm at 600mL, so we could actually use this spastic pressure to help us levitate. In this paper, I propose…