5 ms·
> At 8:16 a.m. on August 6, 1945, a fission weapon containing sixty-four kilograms of uranium detonated 580 meters above the Japanese city of Hiroshima, and Ein
by VBprogrammer 5y ago
> At 8:16 a.m. on August 6, 1945, a fission weapon containing sixty-four kilograms of uranium detonated 580 meters above the Japanese city of Hiroshima, and Einstein’s equation proved mercilessly accurate. The bomb itself was extremely inefficient: just one kilogram of the uranium underwent fission, and only seven hundred milligrams of mass—the weight of a butterfly—was converted into energy. But it was enough to obliterate an entire city in a fraction of a second.
This reminded me of this quote from "Midnight in Chernobyl". Quite amazing to thing of such small amounts of mass being converted into such extraordinary amounts of energy.
- deleted 5y ago[deleted]
- mrtnmcc 5y agoGuess this is saying that the one kilogram of uranium is converted to fission products which are slightly lighter--one kilogram minus a butterfly--and the amount of energy released from this difference is e=(mass of butterfly)*c^2
- shadowgovt 5y agoYeah, the mass-energy relationship is at scales that are hard to wrap a human brain around. A charged laptop battery gains about 2 picograms of mass.
- mrtnmcc 5y agoWait is that right? I thought charging a lithium battery was simply displacing electrons from cathode to anode, but the total number of electrons in the whole battery is conserved (and hence mass). Or is this converting that electric potential into an equivalent mass? Does this actually manifest as a difference on a scale?
- shadowgovt 5y agoThe total particle count is conserved. ... But the total mass of a molecule is also affected by the energy in the chemical configuration; the chemistry of the charged battery has more energy than the uncharged battery. https://physics.stackexchange.com/questions/195696/do-chemical-bonds-have-mass https://physics.stackexchange.com/questions/195696/do-chemic...
- mrtnmcc 5y agoInteresting, so in the context of this broader discussion, if you displaced 1% of electrons in your body by a centimeter, you would weigh 10x more than you did originally. (Both gravitational mass and inertial mass increase)
- wizzwizz4 5y agoAnd then you would die, instantly, and so would the surrounding countryside.
- ninju 5y agoAnd the countryside on the other side of the Earth as well
- p1mrx 5y agoAssuming that you displaced all the electrons in the same direction, you'd produce a 1 cm electron cloud on one side of your body, and 1 cm of electron-deficient matter on the other side. If you could somehow maintain that configuration, you'd have a capacitor storing an enormous amount of energy, so it makes sense that the mass would increase.
- da_chicken 5y agoYeah, this is also why an empty hard drive should have less mass than a full one. It's an immeasurable amount, but it should be there. Adding energy to a system should increase it's mass. https://physics.stackexchange.com/questions/31326/is-a-hard-drive-heavier-when-it-is-full https://physics.stackexchange.com/questions/31326/is-a-hard-...