Talk:Mass/Archive 3

message: Both objects accelerate at the same rate towards the moon, but the moon accelerates towards the hammer faster than it accelerates towards the feather; ergo, the hammer hits the ground first. This isn't an "unsourced claim"; it's physics. Anonymous 198736 03:46, 23 April 2006 (UTC)
replies: text: I guess it's probably true. -lethe talk [ +] 03:58, 23 April 2006 (UTC)
replies: text: Love the Goya painting! :-) Anonymous 198736 04:05, 23 April 2006 (UTC)
replies: text: Do you?  I love it too, it's my favorite painting, and I have a print of it hanging in my kitchen.  But I've lately been getting some harrassment from a crackpot who thinks that my preference for that painting indicates that I rape and murder children. -lethe talk [ +] 04:40, 23 April 2006 (UTC)
replies: text: Not that I know much about him, but I remember being blown away seeing some of his early work compared to his (boringly traditional) contemporaries. Subversive, and sometimes quietly so; this portrait he did of some Spanish noblewoman, around 1800 or so, in the Getty collection, I found particularly impressive. Anonymous 198736 05:48, 23 April 2006 (UTC)
replies: text: de Goya, like Beethoven, was at the forefront of the Romantic movement.  It's my impression that yes, their contemoraries' works seem pretty boring by comparison. -lethe talk [ +] 09:26, 23 April 2006 (UTC)

text: WTF, the hammer and the feather are both pulling the moon in the same direction. Anyway, it doesn't matter if it's true, it matters if it's verifiable. —Keenan Pepper 04:08, 23 April 2006 (UTC)

text: What you're claiming is not as simple as 2 + 2 = 4, and needs a verifiable source. As I said, the two objects are pulling the moon in the same direction. The moon is not accelerating faster toward one than the other. —Keenan Pepper 04:23, 23 April 2006 (UTC)
replies: text: If you drop two objects at the same time, then you're right, the fall at the same rate (and the planet accelerates according to the combined mass).  But if you do two separate experiments, first dropping the heavy object and then dropping the light object, it seems to me that anonymous 19 is right: the heavier object will fall faster.  As for whether this fact is interesting and deserves mention in the article, or whether it requires a source, I haven't made up my mind.  -lethe talk [ +] 04:40, 23 April 2006 (UTC)
replies: text: Okay, you've got a point there. —Keenan Pepper 04:48, 23 April 2006 (UTC)
replies: text: Actually, the hammer lands first even if you drop them simultaneously, since they can't both be dropped from the exact same place at the exact same time. The side of the moon closer to the hammer will accelerate faster than the side closer to the feather. This should be mentioned in the article, since the very possibility seems to have escaped least one person already, even to the point of denial. Anonymous 198736 05:01, 23 April 2006 (UTC)

text: The feather will land first!! (and please don't include this in the article). Let's do a calculation. The mass of the Earth is about 1024 times bigger than the mass of the hammer. Therefore, the acceleration of the Earth is 1024 times smaller than the acceleration of the hammer, so if the hammer falls through 1 m, the Earth will move 10-24 m during the same time. Such short distances, which correspond to an energy of 100000 TeV, are not probed even by the most energetic particle accelerators! Let's now do another calculation. Suppose we're dropping the feather. The hammer, which is presumably on the ground, attracts the feather with its gravity. The additional acceleration of the feather is given by GM/r2, where M is the mass of the hammer and r is the distance from the feather to the hammer. This gives roughly 10-10 m/s2, which is much bigger than the effect suggested by the Anonymous. Yevgeny Kats 05:22, 23 April 2006 (UTC)
replies: text: Of course, that's only if you drop the hammer first and the feather second, which just goes to show how arbitrary and pointless this all is. —Keenan Pepper 05:35, 23 April 2006 (UTC)
replies: text: Well, the article as it currently stands is just plain wrong, so I'm going to go ahead and make the necessary corrections. I'll try not to make it overwordy. Please don't revert it again. Anonymous 198736 05:48, 23 April 2006 (UTC)
replies: text: It's an important fact for the theoretical basis of general relativity that the instantaneous acceleration that a falling object undergoes be independent of the mass of the object.  Two objects should undergo exactly the same acceleration.  If it's not exact, then GR is broken.  So I'm not too happy with the current wording "the hammer and the feather should fall at approximately the same rate".  Nevertheless, I do agree with Anonymous 19 that we shouldn't keep statements that are wrong.  Perhaps we can do better? -lethe talk [ +] 06:16, 23 April 2006 (UTC)
replies: text: Lethe, almost any statement in most articles about physics is approximate. If you fix every such statement you will never get out of it. In our case, the approximation is better than anything one could dream about (as we calculated above), so I suggest that we shouldn't confuse the readers with that. I completely agree with Keenan who said "how arbitrary and pointless this all is". Yevgeny Kats 15:38, 23 April 2006 (UTC)
replies: text: I agree with you, that it's probably bad to have a slavish aversion from things that are only approximately true.  In the current situation, I think the right solution is to just not talk about how long it takes for two objects to hit the ground, and instead only mention the acceleration.  Right? -lethe talk [ +] 23:46, 23 April 2006 (UTC)
thread_title:  Hammer lands before feather 

message: > To date, no deviation from universality, and thus from Galilean equivalence, has ever been found, at least to the accuracy 1/10**12. More precise experimental efforts are still being carried out. <
This part of the article is not true. I am aware of experiments conducted in deep mineshafts with copper and steel balls, which showed quite significant (0.1-0.4%) difference based on material quality. These experiments, however, are DISPUTED (which is not the same as "has never been found"). This issue should be clarified! 82.131.210.162 (talk) 18:07, 9 January 2008 (UTC)
replies: text: Citation please? --Slashme (talk) 05:45, 10 January 2008 (UTC)
thread_title:  Not true. 

message: Someone changed the opening paragraph a couple of days ago, saying mass is a concept of chemistry. Seems to be no discussing here on this talk page to categorize mass as a chemistry concept, so I changed back to physics. Also, the article's categorization doesn't deal with chemistry. Although mass is very important in chemistry, in my opinion it should be viewed as a physical property. Mårten Berglund (talk) 00:38, 20 March 2008 (UTC)
replies: text: I agree. The current definition reads far too closely to the definition of amount of substance, which is definitely different from mass. Physchim62 (talk) 16:30, 14 December 2008 (UTC)
thread_title:  Physics or chemistry? 

message: The last link to http://unification.selfip.org:2008/ is  innapropriate to wikipedia and should be removed. The concept of particle as "a magnetic spherical loop" developped in this "theory" would be regarded as bogus by the vast majority of physicists. If required I can loose my time translating parts of this for you, but I believe it is not worth.  —Preceding unsigned comment added by Humanino (talk • contribs) 15:55, 18 August 2008 (UTC)
thread_title:  (Au sujet de la masse) Origin of Mass 

message: Why doesn't your mass increase by 100 g after you eat a 100g sandwich?  —Preceding unsigned comment added by 71.17.75.192 (talk) 02:26, 15 December 2008 (UTC)
replies: text: You're not a closed system, and you lose carbon when you breathe in oxygen and exhale CO2. Some of that sandwich is carbon. If you put a man in a bubble or sealed spaceship and he eats a 100 g sandwich, mass of the system never changes. SBHarris 00:50, 5 February 2009 (UTC)
replies: text: The mass of the bubble or sealed spaceship (including its contents) system would not change, but the mass of the man-sandwhich system would still change. Brian Jason Drake 09:34, 22 September 2009 (UTC)
thread_title:  {{Anchor|Question}}<!-- This anchor is for the old heading. -->Effect of eating on body mass