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swansont

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Everything posted by swansont

  1. Multiply by 1, and cancel the units 1 km/1000 m =1 3600 s/1 hr = 1 (remember to square the whole thing)
  2. Covering a body part doen't prevent heat escaping it, it just slows it down.
  3. I would agree. Radiation isn't a problem if the energy isn't deposited. Slow neutrons tend to have bigger absorption cross sections - they have a larger deBroglie wavelength and spend more time interacting. Most of the energy they deposit is because of the change in nuclear structure, not due to KE. Using the nuclei under discussion: a C-12 nucleus capturing a neutron with ~0 KE releases ~5 MeV of energy. While neutrons with a large KE deposit that much more energy per interaction, the interaction probability can drop, and the overall danger goes down. (What I was confused about was you asking for a "similar chart" for neutrons, in reference to the Coulomb barrier - neutrons don't see a Coulomb barrier)
  4. I never said the earth was an inertial frame. I did in fact say there were GR effects for which you had to account. Yes, that claim can be made. And the only way to compare the clocks side-by-side is for one of them to undergo an acceleration, so there is no contradiction involved.
  5. In comparison to the stationary clock, i.e. the observer (when in an inertial frame)
  6. Southern democrats are fairly conservative, not liberal, and things have been very different since the 60's. Northern Democrats have done poorly there.
  7. Very basically it's molecules sticking to a surface. The attraction is fairly weak and you don't form a chemical bond, in the case of physisorption (IIRC it's van der Waal's forces) You can usually undo it by heating the solid. A lot of filtration uses this method, like charcoal filtering of water. If you do form a bond, it's known as chemisorption. And if we Google on the right terms...Here is more.
  8. I'd start with the changing the sin(a+b) term using the angle sum identity. Squaring both sides might end up simplifying things
  9. Taxiing down the tarmac, the jetliner abruptly stopped, turned around and returned to the gate. After an hour long wait, it finally took off. A concerned passenger asked the flight attendant, "What was the problem?" "The pilot was bothered by a noise he heard in the engine," she explained. "It took us a while to find a new pilot." --- A man is in a hotel lobby. He wants to ask the clerk a question. As he turns to go to the front desk, he accidentally bumps into a woman beside him and as he does, his elbow goes into her breast. They are both quite startled. The man turns to her and says, "Ma'am, if your heart is as soft as your breast, I know you'll forgive me." She replies, "if your penis is as hard as your elbow, I'm in room 1221." --- "What I've learned" I've learned that you cannot make someone love you. All you can do is stalk them and hope they panic and give in. I've learned that no matter how much I care, some people are just assholes. I've learned that it takes years to build up trust, and only suspicion, not proof, to destroy it. I've learned that you can get by on charm for about fifteen minutes. After that, you'd better have a big dick or huge tits. I've learned that you shouldn't compare yourself to others - they are more **cked up than you think. I've learned that you can keep puking long after you think you're finished. I've learned that we are responsible for what we do, unless we are celebrities. I've learned that regardless of how hot and steamy a relationship is at first,the passion fades, and there had better be a lot of money to take its place. I've learned that sometimes the people you expect to kick you when you're down will be the ones who do. I've learned that we don't have to ditch bad friends because their dysfunction makes us feel better about ourselves. I've learned that no matter how you try to protect your children, they will eventually get arrested and end up in the local paper. I've learned that the people you care most about in life are taken from you too soon and all the less important ones just never go away.
  10. Two engineering students were walking across campus when one said, "Where did you get such a great bike?" The second engineer replied, "Well, I was walking along yesterday minding my own business when a beautiful woman rode up on this bike. She threw the bike to the ground, took off all her clothes and said, "Take what you want." The second engineer nodded approvingly, "Good choice; the clothes probably wouldn't have fit." --- What is the difference between mechanical engineers and civil engineers? Mechanical engineers build weapons, civil engineers build targets.
  11. Not sure what you mean. Neutrons can always be absorbed because they have no charge. They cause ionization directly, by scattering or absorption recoil, and indirectly because neutron absorption usually generates gammas.
  12. No, I meant the mass of (Be-9 + alpha). That mass is 0.01143 amu larger than C-13, so there is an excess of 10.65 MeV that the C-13 would need to shed, and that's ignoring any KE the alpha has to have to overcome the Coulomb repulsion and cause the interaction. That's a lot of energy to get rid of. By emitting a neutron, the C-13 sheds about 5MeV of that excitation.
  13. No, it's real. Moving clocks run slower than stationary clocks. This has been confirmed by a number of experiments and is continually tested by GPS satellite atomic clocks. (There are also effects of general relativity to consider, but the special relativity effects are well-established)
  14. The nucleus can still be unstable after IT. In your example, the Tc-99 ground state undergoes beta-minus decay.
  15. You know if you're in an accelerating frame of reference. (This is a bit of a non-sequitur, since my previous answer was context-dependent.)
  16. By this description you are necessarily invoking a third observer. That observer would see both clocks as the same, if the speed and accelerations are the same.
  17. Gammas are emitted when the nucleus is in an excited state. The nucleus de-excites by emmitting a gamma. Neutron emission can happen with an excited nucleus that has an excess of neutrons - this typically happens after a beta-minus decay that leaves the daughter in an excited state. (This is an important neutron source in nuclear reactors that use thermal neutrons) Proton emission isn't something with which I am familiar, but I imagine it could happen in a way that mirrors the neutron emission - excited nucleus after a beta-plus decay. Neutron and proton emission can also occur in induced reactions.
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