Engineering, 07.03.2020 02:38 ayoismeisjjjjuan
In class we talked about white dwarfs, certain cold stars that are stabilized against gravitational collapse by the degeneracy pressure of their electrons. a) Following the notes, carefully re-derive the radius R for which the total energy of the star is minimum. We are assuming constant density. b) Determine the radius, in kilometers, of a white dwarf with the mass of the sun. Assume that Ne = Msun mp) where Z/A is the ratio of the atomic number to atomic mass number, mp = 1.673 x 10-27 kg is the proton mass, and Msun = 1.989 x 1030 kg is the mass of the sun. For a white dwarf, consider ZA 1/2. The mass of the electron is me = 9.109 x 10-31 kg, the gravitational constant is G = 6.674 x 10-11 m kg-1 5-2, and ħ= 1.054 x 10-34 m² kg/s. c) Estimate a characteristic ne under typical conditions inside a white dwarf. Using the result of (b), and assuming a temperature of T = 107 K, evaluate numerically the ratio ETH EF, where Eth is the characteristic thermal energy of an electron in a gas of temperature T (kBT, where kB = 8.62 x 10-5eV/K is the Boltzmann constant), to see that the electrons inside a white dwarf are indeed degenerate.
Answers: 3
Engineering, 04.07.2019 18:10, bckyanne3
Afull journal bearing has a journal diameter of 27 mm, with a unilateral tolerance of -0.028 mm. the bushing bore has a diameter of 27.028 mm and a unilateral tolerance of 0.04 mm. the l/d ratio is 0.5. the load is 1.3 kn and the journal runs at 1200 rev/min. if the average viscosity is 50 mpa-s, find the minimum film thickness, the power loss, and the side flow for the minimum clearance assembly.
Answers: 1
Engineering, 04.07.2019 18:10, juansoto227711
Journeyman training is usually related (clo2) a)-to specific tasks b)-to cost analysis of maintenance task c)-to control process to ensure quality d)-to installation of machinery
Answers: 2
Engineering, 04.07.2019 18:20, DroctorWellsfan
Inspection for bearing condition will include: (clo4) a)-color b)-smell c)-size d)-none of the above
Answers: 1
Engineering, 04.07.2019 18:20, jessie8022
Apiston-cylinder device contains 0.1 m3 of liquid water and 0.9 m3 of water vapor in equilibrium at 800 kpa. heat is transferred at constant pressure until the temperature of water reaches 350 °c. determine (a) the quality of water at the initial state (b) the work associated with this process, (c) the heat associated with this process.
Answers: 2
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