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May
13
comment Does the Planck scale imply that spacetime is discrete?
Another related: physics.stackexchange.com/q/4453
May
13
comment How do you explain spinning tops to a nine year old?
+1 for the bicycle wheel suggestion. It's a great way to get the point across in a way that can really be seen, and felt. Careful not to catch your nose on the spinning tyre though! ;)
May
13
comment Help getting the distance an object has moved
not only was the question very close to being a "do my homework" type question anyway, clearly not permitted in the FAQ, but your answer has gone one step further and does it. Hence why I phrased my attempt more as a guide than complete calculation.
May
13
comment Maxiumum weight a buoy can float
@Georg - The volume of pressurized are is not meaningless; it has a mass associated with its volume and density. However, I was assuming the walls of the buoy were thin, and the air wasn't significantly pressurized (since this would have a detrimental effect on the buoyancy anyway.) Perhaps I could have stated this but I didn't want to overcomplicate a brief comment.
May
13
comment Maxiumum weight a buoy can float
Buoyancy is related to the weight of the volume of material displaced. In your case this means the max weight would be equal to $3943mm^3$ of water, minus the 0.8kg weight of the buoy..
May
13
revised On black holes, Hawking radiation and gravitational atoms
Typo
May
13
comment Help getting the distance an object has moved
@Georg and @Qmechanic An unusual unit for distance. If that is indeed the case here, well .. fine.
May
13
comment Help getting the distance an object has moved
@Omega - Is there a typo in your unit for the speed? 14hm/min doesn't make any sense..
May
13
answered Help getting the distance an object has moved
May
12
revised Space-time hospitality
added 5 characters in body
May
12
comment Shape of Fan Blades
@Martin - Very interesting, thanks. I wonder whether the same principle work for a water pump? I suspect one would require near-lamina flow from the internal pump to holes but have no idea if this is feasible..
May
12
comment The meaning of action
This is a nice compliment to the others answers but I feel it necessary to point out that the book you cite (QFT Demystified) contains a huge number of errors and in many sections over-simplifies the theory. It should not be considered as a suitable introductory text to the subject, or even one that should be trusted.
May
10
revised Space-time hospitality
Typo
May
10
revised Space-time hospitality
deleted 3 characters in body
May
10
answered Space-time hospitality
May
10
comment Space-time hospitality
Whilst this question is hugely hypothetical (and could have been better worded) I see no harm in considering the requirement of gravity on the possibilty of life. Up-voting to conteract down-votes that I believe to be unfair.
May
10
comment What happens if you try to freeze water in an water tight container
+1 for the great video link
May
10
comment Protons' repulsion within a nucleus
+1 for a perfectly reasonable question. I only wish I'd got an answer in before @Lubosh ;)
May
10
comment Is it pions or gluons that mediate the strong force between nucleons?
@anna I posed this question after having read @Lubosh's answer. I don't feel that it answers my question and, either way, I was kind of hoping for a slightly more expansive answer. When I get a chance I'll add an edit, containing some LaTex, that should better describe why I posted this query.
May
10
asked Is it pions or gluons that mediate the strong force between nucleons?