Physics 30

46 Marks Total ASSIGNMENT 19 Part One: Fission and Fusion Part One of this assignment is worth 21 marks. The value of each question is noted in the left margin in parenthesis. Note: The answer areas will expand to fit the length of your response. 1. Complete the following 12 items regarding nuclear fusion and/or fission. (1) What is observed at the subatomic level when nuclear fission occurs? Answer: A large nucleus breaks up into 2 smaller nucleus and a few neutrons are emitted at the same time. (1) What is observed at the subatomic level when nuclear fusion occurs? Answer: Two small nucleus fuse into one bigger nucleus. (1) In what type of nuclear reactions are the nuclei of elements such as hydrogen, helium, and lithium used? Answer: Fusion (1) Nuclei of elements such as americium and thorium would be used to release energy in a _____ reaction. Answer: fission (1) Name an element which cannot release energy in a fission or fusion. Answer: Iron (1) Compare the abundance of fuel for nuclear fusion and fission reactions. Answer: Nuclear energy can be created through nuclear fission and nuclear fusion. Nuclear fission is the splitting of a heavy atom into two or more parts, releasing huge amounts of energy. The release of energy can be controlled and captured for generating electricity. Nuclear fusion involves bombarding hydrogen atoms together to form helium. In the long run, nuclear fusion has greater potential than fission. (1) Describe two considerations when building a nuclear reactor that would minimize the environmental impact of the nuclear fission reaction. Answer: Not building the plant on an environmental area with lots of ecosystems that is vulnerable to earthquakes and etc. Also, proper waste disposal procedures. (1) Why is there virtually no environmental impact in a nuclear fusion reaction? Answer: Fusion has very good inherent safety qualities, among which absence of 'chain reaction' and no production of long-lived, highly radiotoxic products. (1) Provide an example of a consequence of a nuclear reactor accident on the population of a nearby city or town. Answer: Chernobyl was evacuated on 27 April 1986, 30 hours after the Chernobyl disaster at the Chernobyl Nuclear Power Plant, located 14.5 kilometers north-northwest. The city today is mostly a ghost town, a small number of people live there now. (1) Currently, only _____ is used in the commercial production of nuclear energy. Answer: Uranium (1) Provide one reason why the “other form” of nuclear reaction is not feasible at this time. Answer: Fission would be not be feasible at this time because it releases a lot of energy however it requires a lot of energy for them to split. (1) While the reaction in part 1k is not feasible, the energy of this reaction is important to our planet. Explain why. Answer: Because it’s the same energy that comes from the sun. (3) 2. Use the following fusion reaction to determine the amount of mass that is converted to energy. Show all work. 2/1 H + 3/1 H 4/2 He + 1/0 n + 17.6 MeV Answer: Based on the conservation of mass and energy before and after have to be equal E=mc^2 m=E/c^2 m=2.819831e-12/(3.00e8)^2 m=3.13 x 10^-29g the amount of mass converted is 3.13e-29Kg. (6) 3. The mass of a helium-4 nucleus is 4.0026 u. The mass of an individual proton is 1.0073 u and 1.0087 u for a neutron. Determine the binding energy per nucleon in the helium nucleus in units of MeV per nucleon. Answer: 4/2 He 2(1/0 n) + 2(1/0 P) Delta m=(2 x 1.0073 u + 2 x 1.0087u) – 4.0026u Delta m = 0.0294u Delta m=4.8819844e-26g E=mc^2 E= (4.8819844e-26 g)(3.00e8m/s)^2 E= 4.39e-9 J = 2.7400e4 MeV Per nucleus= E/4 2.7400e4 MeV/ 4 = 6.86 Mev/ nucleon STOP! When you have completed all of the questions in Part One, save your work to your desktop. You will return to this assignment to complete Part Two after you have completed the remainder of the content in the next section. Part Two: The Subatomic World Part Two of this assignment is worth 25 marks. The value of each question is noted in the left margin in parenthesis. Note: The answer areas will expand to fit the length of your response. 1. The following diagram of a bubble chamber shows the paths of an alpha particle, beta negative particle, beta positive particle and a gamma ray (labeled 1 -4). The magnetic field is directed downward (into the page). (1) Identify the alpha particle (by number) and explain the reason for your choice. Answer: 2 because it has a contrary change so it goes deflection. (1) Identify the beta negative particle (by number) and explain the reason for your choice. Answer: 4 because it has a contrary change so it goes deflection. (1) Identify the beta positive particle (by number) and explain the reason for your choice. Answer: 1 because it has a contrary change so it goes deflection. (1) Identify the gamma ray (by number) and explain the reason for your choice. Answer: 3 because it has no charge so it does not get deflected 2. Compare and contrast matter and antimatter. Answer: Antimatter is the same as matter in every way, looks the same, behaves the same, except its particles have electrical charges opposite to matter. 3. Other than the electron-positron, provide an example of a matter-antimatter pair that you have previously studied in Physics 30. Answer: Proton and antiproton 4. (2) The following two questions refer to up quarks changing into down quarks. Write the equation for the conversion of an up quark into a down. Answer: ud+ w+ (2) Show that charges are conserved when an up quark changes into a down quark. Answer: up quark charge is +2/3 and on the down quark is -1/3; the charges are + 2/3 for positron -1/3 + 1= +2/3. 5. (2) The following two questions refer to down quarks changing into up quarks. What particles are involved when a down quark changes into an up quark? (Write the equation.) Answer: du+w- (2) Show that charges are conserved when a down quark changes into an up quark. Answer: down quark charge is -1/3 and for the up quark is +2/3; the charges are -1/3 for electrons +2/3 -1= -1/3. (2) 6. High-energy particle accelerators are used to study subatomic particles. Explain why the particle accelerators must be high energy. Answer: Because you need high energy to break all the internucleon forces in order to separate the particles. (1) 7. Use the charge on quarks to identify the quarks that make up a proton. Answer: +2/3 +2/3 -1/3 = +1 (1) 8. Use the charge on quarks to identify the quarks that make up a neutron. Answer: 2/3 – 1/3 – 1/3= 0 (2) 9. A five quark combination called the pentaquark of theta-plus has been hypothesized to exist. The pentaquark is a combination of two ups, two downs, and one antistrange quark. Determine the net charge on a pentaquark. Show all work and state why the antistrange has the charge it does. Answer: uudd + antistrange 2/3e +2/3e – 1/3e 1/3e + antistrange (2/3 + 1/3)e = +1 it is a proton The net charge is +1. Because the strange quark has a charge of -1/3, the antistrange quark must have a charge of +1/3. (1) 10. Under the Standard Model, which of the following particles is considered to be an elementary particle? Proton Neutron Electron Alpha particle Answer: C 11. (3) An isotope emits an electron and an anti-neutrino during radioactive decay. The electron moves east with a momentum of 9.28 x 10-26 kg? m/s and the anti-neutrino moves north with a momentum of 7.47 x 10-27 kg? m/s as shown in the diagram below. Determine the momentum of the recoiling nucleus. Determine the angle to the nearest 1/100th degree. Answer: Because of conservation of momentum pi = pf Pi = 0 so pf is equal to 0 too. Py of recoiling nucleus is 7.47 x 10-27 kg? m/s [south] because the momentums in the y axis have to add up to 0. Px of recoiling nucleus is 9.28 x 10-26 kg? m/s [west] because the momentums in the x axis have to add up to 0. A2 + b2= c2 (9.28 x 10-26 kg? m/s [west] )^2 + (7.47 x 10-27 kg? m/s [south])^2 = c^2 C = 9.310 x 10^-26 kg m/s tan?= y/x = 7.47 x 10-27 kg? m/s / 9.28 x 10-26 kg? m/s = 0.08023 Tan-1(0.08023) = 4.602 Momentum of the recoiling nucleus is 9.31 x 10^-26 kg m/s [ 4.600 s of w] (1) If scientists only knew where the electron and recoiling nucleus went, which conservation law would lead them to believe another particle must be involved? Answer: The law of conservation of momentum. When you have completed all of the questions in this assignment, submit your work.