Physics In five billion years the Sun will collapse and become a white dwarf. Th
ID: 1482818 • Letter: P
Question
Physics In five billion years the Sun will collapse and become a white dwarf. The radius of the white dwarf will be only 1% of the current value of solar radius (1% = 0.01). You can assume that the total mass of the Sun does not change in the process. You can also assume that both the Sun and the white dwarf are uniform solid spheres. If the initial gravitational acceleration on the surface of the Sun before the collapse is gs, and the acceleration on the surface of the white dwarf gwD, which one of the following statements is true? gs = (0.01) gWD gs = squareroot (0.01) gWD gs = (0.01)^2 gWD gs = gWD gs = (0.01)3/2 gwD none of the above If the initial rotation period of the Sun before the collapse is the rotation period of the white dwar, is TWD, Which one of the following statements is true? TWd = (0.01) Ts TWD = squareroot(0.01) Ts TWD = (0.01)^2TS TWD = Ts Two = (0. 01)3/2 TS none of the aboveExplanation / Answer
Here,
final radius , rf = 0.01 * ro
ro in the current radius of sun
as acceleration due to gravity is given as
g = G * m /r^2
if r will be 0.01 times
gs = (0.01)^2 * gwd
where gs is the current value of g
hence , the correct option is B) gs = (0.01)^2 * gwd
b)
as the angular momentum will be conserved
(2/5) * m * ro^2 * (1/Ts) = 2/5 * m * rf^2 * (1/Twd)
ro^2/Ts = ( 0.01 * ro)^2/Twd
Twd = 0.01^2 * Ts
the correct option is B) Twd = 0.01^2 * Ts