Wiki says people average 1 - 2L per day. Take 2 L, = 67.6 fl oz.
How many times a day does the average person urinate? I say 8, so that gives
~ 8.45 fl oz per piss.
1 fl oz of water weighs 29.574 g or 0.0652 lbs
So I calculate 1 piss weighs ~ 1/2 lb or 1/4 kg.
Can you rig a counterweight on a seesaw such that the trigger point is within 1/2 lb (1/4 kg) of your weight?
I say tricky but possible.
(I once puzzled myself and others how my weight could drop ~ 2 lbs within the course of about 4 hours one day - not exercising/sweating profusely, but working indoors in A/C. Finally figured out I had put coins in vending machines - a couple dollars worth. So no, I didn’t pee that much. )
IMHO no. Yes, with a lot of care you could set the counterweight to be in between your full-bladder weight and your empty-bladder weight, certainly no more than a 20 oz. difference. But I’m not sure you would go from flat on the ground to all the way up from that amount of change.
The real problem, I think, is that if it’s close enough for peeing to make a difference, it’ll also be close enough for small shifts in the person’s position to also make a difference.
The answer to will this work in the real world is obviously “On which seesaw?”. It will work on any seesaw that has less friction than it takes to resist about a pound (1 pint of water) pressing down at whatever distance the seat is from the fulcrum.
It’ll depend on exactly where the two centers of mass are with respect to the pivot axis:
-if the two COM’s can be connected by a line that passes above the pivot axis, the system will be bistable: it will sit with one mass on the ground until a critical amount of mass is removed from that end, at which point it will tilt until the other end smacks the ground. When I donate blood at the local Red Cross place, they have a device that measures out a pint of blood like this: when the pint bag fills up, it’s heavy enough to overcome the counterweight at the other end and the whole thing goes CLUNK, catching the attention of the staff.
-if the two COM’s can be connected by a line that passes through the pivot axis, the behavior is similar to above, but less severe.
-if the two COM’s can be connected by a line that passes below the pivot axis, the stable position will depend on the mass imbalance between the two ends. Remove a small amount of mass from the lower end, and the seesaw will resettle at a new angle, not necessarily thunking the other end all the way to the ground (unless you remove a lot of mass).
Really? That’s once every 3 hours. If you piss less often, and still stay with the max 2L a day, then you piss more at a time.
Admittedly, I pee often, and I doubt there are a lot of pregnant women trying this experiment (not that I’m one of those), but I didn’t think my numbers were way out of line.
Hmm, using weights from the US Mint site, I’m getting $20 in quarters (i.e. 80) or dimes (i.e. 200), or a little less than $10 in nickels (i.e. 40). This happened several years ago, so my memory is fuzzy, but things aren’t quite adding up.
I agree with this; even if his feet don’t move on the seesaw. Altering posture so that his weight moves from the toes/balls of his feet to his heels would produce a greater change in the torque on the pivot than would a weight loss of, say, a liter.
Let’s see; a back of the envelope guesstimate with a 70kg guy who can shift his COG from 220 cm to 200 cm from the fulcrum without moving his feet will produce a change in torque 6.4 times greater than a guy at 220 cm who goes from 70 kg to 69 kg by peeing a liter.
Really? That’s once every 3 hours. If you piss less often, and still stay with the max 2L a day, then you piss more at a time.
Admittedly, I pee often, and I doubt there are a lot of pregnant women trying this experiment (not that I’m one of those), but I didn’t think my numbers were way out of line.
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Actually, Sapo said that. I just implied it.
Also, it’s once every three hours if you get up twice in the night to pee. It’s every two hours if you manage to sleep through the night … I’m taking a diuretic for high blood pressure, and I still don’t pee that often. But I’m sure I do pee more than a cup at a time. Hell, sometimes I feel like Austin Powers waking up from a thirty-year deep freeze hibernation. (Wait, was that TMI?)
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