Physics problem involving isotopes, speed of sound, and interatomic bonds?
Uranium-238 (U238) has three more neutrons than uranium-235 (U235). Compared to the speed of sound in a bar of U235, is the speed of sound in a bar of U238 higher, lower, or the same? There are several factors that play a role. Chemically, the atoms of these two isotopes behave in essentially identical ways, since the number of protons (92) is identical and the clouds of 92 electrons are nearly identical. The interatomic distance, and the effective "stiffness" of the interatomic bond, both depend on the chemical properties of the atoms. Therefore, which of the following statements are true? A). The interatomic distance is the same for the two isotopes, because it depends on the size of the electron cloud, not the nuclear mass. B). The effective stiffness of the interatomic "spring" is the same in the two isotopes, since this "spring" is a model for the interactions of the outer electrons, which are the same for different isotopes of the same atom. C). The effective stiffness of the interatomic "spring" is greater for U238 because the mass is greater. D). An atom with more mass in the nucleus is bigger, so the distance between neighboring atoms is larger.
How is the energy released during a fusion reaction more than that released during a fission reaction ?
it is a known fact that energy produced in during a Fission reaction is less than that produced by Fusion of Hydrogen atoms in the sun.. how is it so .. or why is it so... In Fission it is about ~200MeV.. how much is it in the sun ( only for 1 atom)
How to use radiation detection devices?
When you are surveying for a source of radiation, it helps to know what kind of radiation it is emitting. Most unstable radionuclides emit gamma rays as well as particulate so we can begin with that. Gamma rays are best spotted with a detector that has a high atomic number. A gamma scintillator like NaI is one of the most sensitive. The high atomic number means more of the gamma rays are stopped. Geiger-Mueller counters are gas filled detectors and may also be used as long as you have a bit of metal tubing around them so the gamma strikes them first to create a shower of electrons in the detector. You should take care to survey in a 360 degree arc to make sure that you are locating the direction of the radiation. Also survey not just at waist level. Some sources may be coming from above or below you. To survey for an beta emitting source, you must use a thin window detector. Usually we use a Geiger-Mueller detector with a large thin window (a pancake probe). Here you must be close to the source because betas travel only a few feet in air and are easily shielded by water and dirt. Cloth wipes of surfaces can be taken and then held up to the detector to check for removable contamination. Alpha radiation with no associated gamma is a very difficult problem. You must survey within an inch. The best survey instruments are usually alpha scintillators like ZnS. A big problem is that you can either contaminate or damage your probe while surveying for the radiation. Some detectors useful on humans include gas-filled proportional counters that can see beta and alpha radiation. They have thin windows that can allow the alpha to penetrate. The problem they have, besides breaking the window, is that natural alpha from radon (a uranium daughter found in soil) confuses the counter into thinking there is contamination of a different source. To search for very low energy betas, for example from tritium (hydrogen-3), liquid scintillation is used. Here the sample is usually water and a small bit of it is mixed with the actual detector fluid. The flash of light in the fluid corresponds to the amount of radiation in the sample. The light, as in all scintillation detectors, is picked up by photomultiplier tubes and relayed to a counter. Hope this helps.
Why don't we enforce our border with barbed wire or an electric fence?
I mean, if Mexico is such a problem, why not? The least we would have to do is razor wire. Or if we are feeling a little weight in our wallets we could get an electric fence. It's not like an accident if someone dies trying to hop it as they know it is an illegal action and in my opinion, is pretty harmful to your health ( ; ] )
Black hole question...?
It takes infinite time for objects falling into a black hole to dissappear into the event horizon. Therefore one of the black holes will emit radiation, but at an ever decreasing rate since the event horizon will steal more and more of the energy of the escaping radiation. The radiation will also be more and more red-shifted, so that the gamma rays will eventually become x-rays, then visible light, then infrared, etc. So the answer is b tending toward d. The pineapples would probably also release a lot of radiation as they're being torn appart near the event horizon, so the b answer is streaching the point pretty thin.
Which Uranium is used to create the breeder reactor?
B The Breeder Reactor was developed to use uranium-238. Here's how it works. A reactor is built with a core of fissionable plutonium, Pu-239. The plutonium-239 core is surrounded by a layer of uranium-238. As the plutonium-239 undergoes spontaneous fission, it releases neutrons. These neutrons convert uranium-238 to plutonium-239. In other words, this reactor breeds fuel (Pu-239) as it operates. After all the uranium-238 has been changed to plutonium-239, the reactor is refueled. However, there are some major problems with the breeder reactor. To begin with, plutonium-239 is extremely toxic. If an individual inhales a small amount, he or she will contract lung cancer. Also, the half-life of the material is extremely long, about 24,000 years. This could create an almost impossible disposal problem if large amounts of this material are generated. Also, because of the nature of the reactor core, water can't be used as a coolant. Instead, liquid sodium must be used. In the event of an accident a catastrophe could develop because sodium reacts violently with water and air. Although the breeder reactor could solve the uranium fuel problem, there are still a number of other problems that will have to be worked out.
Why can't we use nuclear fuel to power space craft?
In the late 1960s and early 1970s, there was a NASA and US Atomic Energy Commission program called NERVA , which worked to develop spacecraft propelled by nuclear fission*.Specifically, NERVA was based around a form of nuclear thermal propulsion: Run a fission reactor as hot as it can be safely run, send fuel into it to be superheated, and expel the fuel out of the rocket at extremely high speed. In principle, nuclear thermal propulsion can provide more velocity change per unit mass of fuel than chemical rockets and more acceleration than electric propulsion **.But the NERVA engine tests demonstrated a problem: Parts of the reactor being eroded and carried away in the rocket exhaust. Despite significant work to try and develop a reactor design with less erosion, the problem has never been solved.So nuclear thermal rockets are not used because they are unreliable and extremely dangerous - and because they have a tendency to irradiate their surroundings. And the Space Shuttles and all other spacecraft launched from Earth have used chemical rockets to go from Earth’s surface into space.* There was a similar program called RD-0410 by the Soviet space program, which likewise did not go beyond test-stand demonstrations.**Nuclear electric propulsion, using the heat produced by nuclear fission to produce electricity and then using that electricity to accelerate propellant, is much more promising than nuclear thermal propulsion. However, while electric propulsion can provide very large total velocity changes for a spacecraft, it can only provide relatively low acceleration. So you can’t use electric propulsion to launch a spacecraft from a planet’s surface. Instead, spacecraft using electric propulsion are launched into space on chemical rockets and then accelerate slowly and steadily once they’re already in free-fall.