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Author Topic: How do you weigh an astronaut?  (Read 5132 times)

Offline chris

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How do you weigh an astronaut?
« on: 23/07/2009 21:10:37 »
A pair of scales won't work in space under micro-gravity conditions, so how do astronauts keep an eye on their "weight" ?

Chris


 

Offline turnipsock

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How do you weigh an astronaut?
« Reply #1 on: 23/07/2009 23:54:13 »
is this an inertia balance thing again?



I remember these things from school, they were at waist hight and positivly dangerous in hands of a schoolboy.
 

lyner

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How do you weigh an astronaut?
« Reply #2 on: 24/07/2009 22:03:43 »
Boinnnnnnng!
 

Offline chris

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How do you weigh an astronaut?
« Reply #3 on: 24/07/2009 22:13:57 »
Is this some sort of in-joke to which I am not party?!
 

Offline Soul Surfer

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How do you weigh an astronaut?
« Reply #4 on: 24/07/2009 23:32:31 »
It is one of the possible answer sto yor question yo gonnect yourself to a spring and mesure your oscillation frequency in comparason to a similar known weight oscillating on that spring
 

Offline turnipsock

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How do you weigh an astronaut?
« Reply #5 on: 24/07/2009 23:35:39 »
I'm sure this was asked before and there was a special chair they sat in that was a basically an inertia balance.

http://www.iki.rssi.ru/mirrors/stern/stargaze/Smass.htm there is a bit about it here.
« Last Edit: 24/07/2009 23:40:21 by turnipsock »
 

lyner

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How do you weigh an astronaut?
« Reply #6 on: 24/07/2009 23:45:39 »
Is this some sort of in-joke to which I am not party?!
Hey Chris - are you havin' a party?
Count me in.
 

Offline Bored chemist

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How do you weigh an astronaut?
« Reply #7 on: 25/07/2009 18:34:10 »
You don't need to weigh astronuats in orbit. Their weight is (practically) zero.

Of course, you might want to keep an eye on their mass and for that an inertia balance would be good, or you could swing them round on a rope with a spring balance in it. If the rotational speed and length of the rope were right you could use an ordinary spring balance or set of bathroom scales with the same calibration as on earth.
 

Offline neilep

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How do you weigh an astronaut?
« Reply #8 on: 25/07/2009 19:27:58 »
It's always down to me again !!

sheesh !!

Take one astronaut, one pair of scales and another object..... here......... for instance I have chosen a planet called Earth,

Whack em on the scales and et voila !

As ewe can see..both planet and astronaut weigh the same !!

hmmmm !!






 

Offline Stefanb

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How do you weigh an astronaut?
« Reply #9 on: 25/07/2009 21:17:27 »
Use a scale that determines mass to find the mass of the astronaut. Then multiply the mass by the amount of gravity (in m/s) and you have your weight
 

Offline Bored chemist

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How do you weigh an astronaut?
« Reply #10 on: 26/07/2009 14:39:28 »
Use a scale that determines mass to find the mass of the astronaut.  and you have your weight

OK
"Use a scale that determines mass "
For example?
"Then multiply the mass by the amount of gravity (in m/s)"
Wrong units; that's a velocity not a measure of gravity.

"and you have your weight"
Since the local gravity is zero when you multiply the mass of the atronaut by zero you get zero. Like I said, you don't need to weigh him; he's weightless.
 

Offline lightarrow

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How do you weigh an astronaut?
« Reply #11 on: 26/07/2009 16:00:56 »
Another possible way (already discussed somwhere in this forum) is to send  a small object (example, a ball) of known mass to the astronaut, at a specific speed and then measure the (astronaut+object)'s final speed after the anelastic collision (the object stay attached at the astronaut).
Because of momentum conservation, indicating with:
M = astronaut's mass
m = ball's mass
v = initial ball' speed
V = (astronaut+ball)'s final speed
you have: mv = (M+m)V and so

M = m(v/V - 1)

Example: m = 1Kg; v = 1 m/s; V = 1cm/s = 0.01m/s  --> M = 99Kg
« Last Edit: 26/07/2009 16:02:38 by lightarrow »
 

lyner

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How do you weigh an astronaut?
« Reply #12 on: 26/07/2009 16:13:12 »
Sounds fun! Dodgeball in a space shuttle.
 

Offline lightarrow

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How do you weigh an astronaut?
« Reply #13 on: 26/07/2009 17:01:22 »
Sounds fun! Dodgeball in a space shuttle.
It could be useful to keep their reflexes alive... :)
 

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How do you weigh an astronaut?
« Reply #13 on: 26/07/2009 17:01:22 »

 

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