Aerospace engineer here. To levitate, the force of the exhausted mass flow (F=ṁ×v) has to equal the pull of gravity (F=m×g) 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=m×g/ṁ=62kg×9.81N/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 0.066mm² 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 to about 0.23km/h, reaching a height of 4cm. If you took your special bladder to space, we can use the rocket equation to calculate that this stunt would accelerate you to 3041m/s×ln(62kg/61.6kg)=19.7m/s=71km/h
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.
For reference, 3 km/s is approximately Mach 10
It’s not a question of if your urinary tract will explode, but where.
we can rebuild him we have the technology
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
But reinforcement makes you heavier and you’re back to the drawing board!
It might be easier to first chop arms and legs off to save the excess weigh.lt.
Will the density of my pee affect this?
frantically starts drinking heavy water
I implemented a realistic physics simulation that answers this question for Diarrhea.
wow I just checked out the source, and as a physicist I can verify that some of those fluid dynamic models you implemented are very cutting edge
“realistic” lol
This was exactly what I thought of when I saw the post! I’m glad you saw this and shared your work here. It’s awesome and it makes me so happy.
Beautiful … bookmarked and saved … my personal best so far is 1023 m
Enough that your abdomen would likely explode from the pressure. Which would make some percentage of your body fly, technically.
This sounds like the perfect thing for whatif by xkcd
According to one of my favorite shorts of all time, the answer is “I don’t know”
Those are the questions I come to Lemmy for
