Naked Science Forum

General Science => Question of the Week => Topic started by: Adam Murphy on 07/06/2018 15:02:50

Title: QotW - 18.06.07 - Weighing things in space?
Post by: Adam Murphy on 07/06/2018 15:02:50
Chris Taylor asks:

If there's no gravity in space, how do astronauts weigh things?

What do you think?
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: Janus on 07/06/2018 16:40:28
Since mass does not depend on gravity, and weight is really just a measure of the force of gravity acting on your mass, they just provide an another type of force to replace gravity.    For small items, you can put them in a centrifuge spun up to a set  speed and measure the centripetal force.
For the astronauts themselves they use a couple of devices.  With one, you sit in it and then it applies a set force to you, how your body moves in response to that force gives you your mass.  The other use a set of springs which the astronaut "bounces" on, and the forces generated are measured and use to calculate the mass.
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: chris on 10/06/2018 12:18:06
So what does this device look like then? Does anyone have a picture?
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: Janus on 10/06/2018 15:14:47
So what does this device look like then? Does anyone have a picture?
https://www.airspacemag.com/daily-planet/how-do-astronauts-weigh-themselves-space-180953884/
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: Colin2B on 10/06/2018 17:43:29
I assume the device has to move the astronaught far enough that any wobbly bits are fully accelerated?
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: katieHaylor on 27/06/2018 13:53:17
This question has now been answered, and you can listen to the answer here: https://www.thenakedscientists.com/articles/questions/qotw-how-do-you-weigh-things-space (https://www.thenakedscientists.com/articles/questions/qotw-how-do-you-weigh-things-space)
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: AlanM on 26/09/2018 10:13:39
I can't think of any good reason for an astronaut to weigh anything.  I would rather use the time saved to eat my sarmies, or some more beneficial activity. 
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: Veer on 29/10/2018 14:20:46
As there is no gravity in the space therefore the objects weighs there Zero(0).
But the celestial bodies like moon and all,HAVE SOME GRAVITY WHICH MAKES THE OBJECT TO BE HAVE A WEIGHT WHEN MEASURED.
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: chris on 29/10/2018 21:14:28
As there is no gravity in the space...

What ARE you talking about? How do you think the moon orbits the Earth or the Earth orbits the Sun then?
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: Bored chemist on 29/10/2018 21:17:24
As there is no gravity in the space...

What ARE you talking about? How do you think the moon orbits the Earth or the Earth orbits the Sun then?
In fairness, what he is talking about is the fact that astronauts are weightless.
They have no weight.
Their weight is zero.
The weight of everything round them is also zero.

What is there to weigh?

However, it's still useful to measure the masses of things.
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: chris on 30/10/2018 20:10:59
Thank; but what I'm disputing is the claim that there is no gravity in space.
Title: Re: QotW - 18.06.07 - Weighing things in space?
Post by: Bored chemist on 30/10/2018 20:30:47
There is gravity so he's mistaken about that, but his point is valid. There is (practically) no weight.