When you eat a sandwich in space flight, does your craft lose mass?

Any thread that makes me think is a good thread.

even if it is a simple thought such as a sandwich and a space ship.

reply to post by Darkblade71


Seconded. A lot of ground has actually been covered in this thread. No opportunity to learn or think differently is wasted.

And, anyway, I've still gotta do my weighing experiment. Can't abandon the thread for at least another 24 hours.

reply to post by CLPrime


I think i will have to concede i now believe you might be correct after doing some research and learning a lot which is why i like this place no mass would be lost unless physically ejected outside. i`m not sure i can explain fully at this time of night but this is what i read below to come to my conclusion

en.wikipedia.org...
en.wikipedia.org...
en.wikipedia.org...
en.wikipedia.org...
en.wikipedia.org...

Thanks for a great discusion everybody and remember everydays a school day.

reply to post by Illustronic

Is energy consumption measurable in mass turned to energy and does energy weigh anything?

You lose the mass you consume mostly in water: sweat, urine, whatever. Solid waste is excreted. Plus, I suppose, the carbon in the carbon dioxide you exhale. All of this is captured by the spacecraft life-support system and most of it is recycled. The spacecraft loses a little mass due to leaks in the system, etc. In theory it loses none.

Energy consumption is measurable as mass turned to energy, sort of. You could calculate the expenditure in calories needed to turn one gramme of human tissue into water, carbon dioxide and some additional waste products. However, this conversion does not result in any loss of mass. You would have, as Phage said, to witness the direct conversion of mass to energy, as in a nuclear explosion. That doesn’t usually happen when I go to the bathroom, though sometimes the sound... never mind.

reply to post by Illustronic

Originally posted by Illustronic
reply to post by Darkblade71

 

That makes sense to me.

Darkblade has got the idea perfectly.

Now, as for your reply to RogersTigers...

In microgravity we observe another phenomena that supports the ToR and basic gravitational thermodynamics. That bodies in the vacuum of space attract, and in microgravity the bodies themselves would defeat the gravitational attraction of a distant larger body and attract each other, if the distance is right. I suspect the human 'dander' attaches itself to the walls and floors and ceilings of the ISS before it just floats around endlessly, but I suppose some time elapses before the dust settles so to speak. I do suppose a liquid spill on the ISS eventually attaches itself to the container walls also. So cleaning may not be as big of an issue as I first thought.

Just for fun, let’s calculate the force exerted by gravity between a forty-tonne spacecraft and half a gramme of earwax at a distance of one metre from each other. Turns out to be 0.000000000001 newtons. This would accelerate the earwax towards the spacecraft hull at 0.000000002 metres per second per second. It would take half a day (give or take a zero in my calculations) for the earwax to travel one metre and strike the spacecraft hull. This ignores the retarding effect of air resistance, which will be significant even in the case of earwax and quite marked in the case of substances such as bellybutton fluff.

However, there is an additional complication. All these icky little fragments are floating inside the spacecraft. They are surrounded by it, and it will attract them (and they it) on all sides. Most of these opposing forces will cancel each other out, with a resultant very small force in a single direction. With this reduced force acting upon them, the roach snacks will barely accelerate at all.

Meanwhile, they are subject to air currents and impacts with other moving bodies (sleeping astronauts’ lips and nostrils, for instance) which will probably ensure that they stay in circulation indefinitely.

Or get swallowed.

And of course, we should never forget that a lot of stuff bounces...

But wait!

The earth gravity on the ISS is still the strongest force for dander, I suspect most land on the floor if the floor is closer to the earth, to them it really doesn't matter, once dander is attached to a wall earth gravity wouldn't move it from there, hence, microgravity.

Is the spacecraft in Earth orbit? Then it is in free fall and so is everything inside it. The spacecraft is already falling towards Earth as fast it possibly can, and all the objects inside it share that acceleration. They're not falling any faster and they won’t stick to anything. Unless they're naturally sticky, of course.

Like earwax.

If a tree falls in space...?






Nevermind, it's in freefall.





What a silly thread.

reply to post by Astyanax


Well it is a good thing I am not in space dodging ear wax because now there would be coffee spewing in the same direction at a high rate of speed, overtaking anyone and some bellybutton fluff in its way as I laugh/choke hysterically at this thread!

A great way to wake up, I needed that smile.

reply to post by Illustronic




The answer is yes because part of that sandwich is converted to energy which is massless. But wait. Some of that energy, and all of it in time, will be used to invigorate the body which heats in response. This heating causes expansion which necessitates more water and fluids be formed so the answer is no because I said so.

Good thread; it got me thinking. Obviously, the reflexive answer is "no." At any reasonable scale mass would be conserved. Then I started thinking about unreasonable scales. Rather than an ordinary solar system roundabout, imagine a huge multi-generation starship moving through space. Over time, naturally occurring radio-isotopes would be ingested by the crew, and these isotopes would decay. There would be a miniscule loss of mass as this happens, but over the aeons...

reply to post by Illustronic


I have a similar question thats of the upmost importance. Its been bugging me for years and im feeling a little immature right now so here goes.

In zero gravity if one were to fart, and im talking a good long one that makes your pants fit better afterwards, will it propel you forward at ANY rate of speed?

My hypothesis is that it would to some degree but i have yet to have access to a zero gravity environment to test this.

I had to ask

reply to post by syrinx high priest


Oh no. I read the post about poo, then the post about tang. Now all I can think about is poo-tang is space.


And to be on topic - you wouldn't have a decrease in total mass .

reply to post by StratosFear


I can't believe I'm answering this question, but here it goes...

First of all, the answer to the question is yes. You will experience some amount of thrust. That's exactly (well, almost exactly) how rockets work.

Now, to see how much thrust will be provided:

Let's say a person has a mass of 75 kg (so, they weigh 165 lbs).
I'm not sure who figured this out, but, apparently, the average fart has a mass of 0.0371 gram, or 0.0000371 kg, and exits with a speed of about 3 m/s. This is a momentum of 0.0001113 kg*m/s.
The person, then, will move in the opposite direction with the same momentum. This translates into a speed of 0.000001484 m/s, or about 5.34 mm/hour (12.8 cm/day; 5 inches per day).

There. Now, go, spread this knowledge to everyone you know.

At this point in time I would like to interject an antidote my smarter and older brother said during the time the whole family ate dinner together when someone said something stupid, "that's as funny as a fart in a spacesuit".

The funny thing is at my age I was picturing an actual fart dressed in a spacesuit instead of an astronaut farting and found the image in my head hilarious!

CLPrime have you calculated the type of clothing the astronaut has on? In the 70's it could have been Polyester. I suspect cotton today would keep the fart thrust closer to the vest and cancel it out to some very measurable degree.

reply to post by Illustronic


If the clothing prevented "it" from escaping, then there would be no thrust at all. If it's a porous material, then some may escape, but (ha...butt) the resultant thrust would be negligible. In order for a fart to provide thrust, it must exit the system...which, in this case, is the person and anything they're wearing.

Originally posted by buster2010
Actually a small amount of mass will be lost. Because part of the sandwich will be turned into energy after it is eaten and then the person would burn the energy off.

Matter can be converted to energy (think of a nuclear bomb), but metabolic processes are NOT converting matter into energy.

A body's metabolism may use matter to transfer energy stored up in food matter, but it does not convert matter into energy.

I don't want to bring in to question the idea of lost mass should a match be close the 'thruster', I already know the answer, flames or not.

In a roundabout way to me this brings us to the idea that our biological system continuously is made up from different atomic elements, some organs faster than others. This doesn't suggest that atomic elements are lost however. The elemental atoms that make up your molecular cellular structure are indeed not the same atoms they were in the past, white blood cells regenerate as soon as they attack what they control in your body, elemental mass is not lost, it is bound to different molecules after the cell dies and new cells form from different atoms, with the parent cell guiding the system of cellular reproduction.

Atoms don't change elements due to chemical reactions (the combining of different atoms to form molecules, or the disassembly of said molecules). The only way that an atom can become a different element is through a nuclear reaction. During a chemical reaction, energy can be released (or absorbed) by breaking or forming molecular bonds between atoms. Atoms themselves have been here since their genesis, and some as far back as the Big Bang, (if they never encountered a black hole or fissioned into a heavier element by a star/gravity).

reply to post by Illustronic

Obviously a body is losing matter all the time (through respiration, perspiration, expelling of waste), but when a body does so in a sealed environment such as a spaceship, that matter will stay in the sealed environment of the spacecraft (until disposed of or vented)

And since all that matter will stay in the spacecraft, the amount of mass will remain the same.

reply to post by CLPrime


It was a question that came up while drinking with some buddies so i had to ask. Im sure others have thought about this to.

Kind of makes me laugh thinking about somebody in NASA might`ve had to answer this same question when the space program started years ago. My day just got a little brighter.

Love this thread. I have wondered many times about what energy is really. Ok, it's needed in order for labor te be done. Nice definition that doesn't get me anywhere.
EM: an electric field and a magnetic field at a 90 degree. How big are these fields? In other words what is the dimension of a photon?

And is there an in between fase between energy and matter? What if we could look at a decaying atom which was taped and then shown very slow motion?

reply to post by QueenofWeird


Not a decaying atom, but at particle colliders (accelerators) like the LHC, atoms are cooled to near absolute zero, (when energy ceases to have motion, theoretically), but this is how they separate protons to send off into near light speed to collide. If you want to see what a slowed down atom looks like, I would start there, (though there are other accelerators that use the same method of colliding a particle of atoms).