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Godcanthelp
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Homework Statement
When a star like our Sun exhausts its fuel, thermonuclear reactions in its core cease, and it collapses to become a white dwarf. Often the star will blow off its outer layers and lose some mass before it collapses. Suppose a star with the Sun’s mass and radius (the radius of the Sun is 6.96×108m ) is rotating with period 25 days and then it collapses to a white dwarf with 53% of the Sun’s mass and a rotation period of 131 s.
Homework Equations
Conservation of Angular Momentum:
Angular Momentuminitial = Angular Momentum final
Angular Momentum = Rotational Inertia (sphere) * Angular Velocity (ω)
Rotational Inertia (sphere) = 2/5MR2
The Attempt at a Solution
ωsun = 2∏/(25*24*60*60) rad/sec
ωwd = 2∏/131 rad/sec
Isun*ωsun = Iwd*ωwd
(2/5)*Msun*Rsun2*2∏/(25*24*60*60) = (2/5)*Mwd*Rwd2*2∏/131
Msun*(6.96*108)2*1/(25*24*60*60) = 0.53*Msun*Rwd2*1/131
(6.96*108)2*1/(25*24*60*60) = 0.53*Rwd2*1/131
Rwd2 = 131*(6.96*108)2*1/(25*24*60*60) *1/0.53
Rwd = 7.44526*106m
Which is incorrect.