What, if any, effect does gravity have on urination?
Is it harder to urinate on Pike’s Peak (14,000 feet) than at sea level, because of the reduced gravitational pull? Does velocity increase with gravity?
What about in the space station or space shuttle, where there is essentially no gravity?
What about peeing in the ocean while scuba diving, because the body is being pushed towards the surface because it has less density than the water? That’s sort of working against gravitational pull.
What’s the effect?
Observing members:
0
Composing members:
0
13 Answers
I can only tell my experience in the sea.
It’s harder (to pee).
Although I don’t think pressure (or gravity, in the mountain example) has anything to do with it.
The bladder squeezes the urine through the pee pipe and we use our sphincter to let it flow.
I might be wrong about the gravitational pull being of no factor.
This is a piss-poor quesion.
The gravitational difference between Pike’s Peak and seal level is minimal, and the pee goes down. I doubt you can measure the difference in velocity while factoring out muscle expression. And as far as velocity is concerned, the slightly lower gravity is more than compensated by the lack of air pressure at altitude. That’s why you can hit more home runs in Denver than in New York.
The issue with peeing while scuba diving has more to do with contractions caused by being surrounded by colder water. Just ask George Castanza.
Gravity makes the urine go in a specific direction and not all over you and anything else that’s around.
In the space station, a vacuum is provided to suck the urine into a disposal/storage place.
In the ocean, urine tends not to be a problem because the person peeing isn’t going to try to stand/float/buoy in one place and the urine will disperse quite rapidly.
@zenvelo Lurve for your perfect opening remark!
I’ve heard of teeing up but not peeing up!
@janbb, oh, yes, you have, as the mother of boys. We used to keep a cloth diaper next to the changing table. We called it the “gotcha!!” diaper. Dropped it on quick when the diaper came off.
Now that everyone has turned silly, let me bring the real question back.
read this article
Apparently gravity does increase flow speed.
@Jeruba You’re right! How quickly we forget!
Gravity is gravity, and “it never differs much from 32.1740 feet per second per second. (Disregarding air resistance.) ” – from The Wonders of Physics – a deluxe Golden book – Golden Press – New York – copyright 1966 by Western Publishing Co. Inc.
So the speed of pee as it pertains to how fast it comes out is of no real consequence. I can pee faster by tightening my bladder muscles, but anyone can do that anywhere. And if I take a whizz off the top of the Empire State Building, the pee might hit the sidewalk at the same speed whether I pushed it out or just let it dribble. It can only fall just so fast and no more.
The gravitational force of Earth is proportional to the square of the distance to the center, which is about 4000 miles. A difference of a few thousand feet is negligible.
In mathematical terms, since there are about 5300 feet in a mile, the ratio of 14000 feet to the radius is about 14000/(4000*5300), which is about 7*10^-4, and squaring that is going to be less than one part in a million.
I think age is more of a factor than gravity.
Answer this question 
This question is in the General Section. Responses must be helpful and on-topic.
Composing members:
0
