The discussion revolves around the behavior of a large amount of mercury in space, specifically in a zero-gravity environment at room temperature. Participants explore the implications of mercury's density, cohesiveness, surface tension, and gravitational effects on its form and stability.
Participants express differing views on whether mercury will collapse under its own weight in zero gravity, with no consensus reached. Some assert it will remain stable, while others question the conditions under which it might collapse.
Participants have not fully elaborated on the assumptions regarding the cohesive properties of mercury or the specific conditions being considered, leading to some ambiguity in the discussion.
Readers interested in fluid dynamics, gravitational effects on liquids, and the properties of mercury in unique environments may find this discussion relevant.
So, what do YOU think will happen, and why?Dhanush Shenoy said:Assume 20°c, ie 1.2mmhg
If possible, assume any other favourable condition
This question makes it sound as though you are posing a question regarding a sphere of mercury. Your original question seemed to be asking about a more random distribution of mercury. Please clarify what you are asking. Exactly what are the starting conditions that you want considered?Dhanush Shenoy said:Since mercury has a high surface tension and cohesiveness, due to its large density will there be any force from the surface to the centre
Dhanush Shenoy said:A sphere of liquid mercury, in zero gravity. Since there will be gravity at its centre, accompanied by surface tension and cohesiveness, will it collapse
No, a sphere of mercury would have no reason to collapse, as it is hardly compressible at all. It will simply remain a sphere. I'm not sure about surface evaporation but the cold of space will have a much more immediate effect. The ball will freeze since the temperature of space is about 3 degrees absolute.Dhanush Shenoy said:A sphere of liquid mercury, in zero gravity. Since there will be gravity at its centre, accompanied by surface tension and cohesiveness, will it collapse
Dhanush Shenoy said:So there won't be any force on the surface from its core?
So the centre will exert some force on the surface and vice versa, How much small the sphere can get?ZapperZ said:Who says that?
I pointed out your claim "... gravity at its centre ... " is not necessarily correct.
The force at any point is due to the sum of ALL the forces from a unit volume of the object. After all, you are on the surface of the Earth and you are not floating in space with no gravity, are you?
Zz.
Thank you, I'm talking about zero gravity and room temperature.phinds said:No, a sphere of mercury would have no reason to collapse, as it is hardly compressible at all. It will simply remain a sphere. I'm not sure about surface evaporation but the cold of space will have a much more immediate effect. The ball will freeze since the temperature of space is about 3 degrees absolute.
Dhanush Shenoy said:So the centre will exert some force on the surface. How much small the sphere can get?
Why mercury, is because of its density and cohesive propertyZapperZ said:This is getting to be very puzzling. Why are you ignoring the repulsive forces between the Hg atoms? Why do you think it will "collapse" in zero g, but not when it is on the Earth's surface? Why would you consider that Hg liquid will collapse, while water doesn't, especially when water has an added property of having a more pronounced surface tension?
You have provided VERY little effort in elaborating the issues here.
Zz.
Dhanush Shenoy said:Why mercury, is because of its density and cohesive property
I'm sorry if I'm wrong or disturbing with silly questions. Mercury tends to stick to each other more than water does. So I wanted to know if a large amount mercury is kept in zero gravity (room temp), will it become a sphere? If it does due to its large density, will there be a high density core? Will there be Any force from the core to the surface? And it has a very less viscosity, will this help in any way to becoming a stable sphere? If so the centre is higher density so will it create a gravity and holds the sphere intact?ZapperZ said:You have explained nothing. What "cohesive property"? Why is this cohesive property that you are using not relevant when we have Hg on the Earth's surface? Why hasn't it collapsed onto itself? Why do you think it will collapse onto itself in zero g?
Water also has a cohesive property. The hydrogen bond and the weak polar properties of water all contribute to that! Why won't it collapse in space? After all, those astronauts have to drink!
Zz.
Yes, clocks floating on the surface of a planet-sized blob of mercury would tick very slightly slowly as compared with clocks far away.Dhanush Shenoy said:If it becomes small and very heavy the time will slow in the vicinity isn't it?
Thank youjbriggs444 said:Yes, clocks floating on the surface of a planet-sized blob of mercury would tick very slightly slowly as compared with clocks far away.
However, smaller (and, accordingly, less massive) blobs would show a smaller effect from this. Heavier (and, accordingly, bigger) blobs would show a greater effect. The effect scales with gravitational potential. Gravitational potential is inversely proportional to radius and directly proportional to mass which is, in turn, reasonably proportional to the cube of radius. Unless density varies dramatically, the mass term wins and bigger blobs have bigger effects at their surface.
This explains, thank youKhashishi said:Something similar to the Chandrasekhar limit should apply. https://en.wikipedia.org/wiki/Chandrasekhar_limit
The threshold for collapse will be somewhat different for mercury than for white dwarf material, but I suppose it can't be too far off.