In a fully degenerate gas, all the particles have energies lower than the Fermi energy For such a gas we found (Eq, 4.19) the relation between the density n, and the Fermi momentum p: 8T 3h3 PF a. For a non relativistic electron gas, use the relation pF = /2m between the Fermi momentum, the electron mass me, and the Fermi energy Er, to express Ef in terms of ne and me b. Estimate a characteristic ne under typical conditions inside a white dwarf. Using the result of (a), and assuming a temperature 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, to see that the electrons inside a white dwarf are indeed degenerate.

Asolid round steel rod 6.25 mm in diameter and 375 mm long is rigidly bonded to the end of solid square brass rod 25 mm on a side and 300 mm long. the geometric axes of the bare are along the same line. an axial tensile force of 5.4 kn is applied at the extreme ends of the assembly. for steel e = 200 gpa and for brass e = 90 gpa. determine the total elongation for the assembly.

The law of the conservation of momentum says that the total momentum of any closed and isolated system cannot

1. what is the relationship between wavelength and the penetrating power of an electromagnetic wave? a) the penetrating power has no relationship to the wavelength. b) the penetrating power increases as the wavelength increases. c) the penetrating power decreases as the wavelength increases. d) the penetrating power decreases as the wavelength decreases. 2. as ice melts and turns into water, the speed of sound through the material would most likely do what? justify your answer. a) the speed would not change because the material is always water. b) the speed of sound would increase because the density of water is less than that of ice. c) the speed of sound would increase because energy is added to ice in order to make it melt. d) the speed of sound would decrease because sound travels faster through solids than liquids. 3.which of these waves need a medium to travel through? a) sound b) x-rays c) infrared rays d) visible light