A star with an intial radius of 1.00 x 10 8 m and a period of 30 days collapsess

Question

A star with an intial radius of 1.00 x 108m and a period of 30 days collapsessuddenly to a radius of 1.00 x 104m. (a) Find the period of rotation after collapse. I got 2.6 x 10-2 seconds. (b) Find the work done by gravity during the collapse if themass of the star is 2.00 x 1030kg. I know that: Work= 1/2 (final moment of inertia) (finalangular velocity)2 - 1/2 (initial moment of inertia)(initial angular velocity)2 Final Moment of Inertia= (2.00 x1030 kg * 1.00 x 104m) Initial Moment of Inertia= (2.00 x1030 kg * 1.00 x 108m) How do I find the intial andfinal angular velocities? A star with an intial radius of 1.00 x 108m and a period of 30 days collapsessuddenly to a radius of 1.00 x 104m. (a) Find the period of rotation after collapse. I got 2.6 x 10-2 seconds. (b) Find the work done by gravity during the collapse if themass of the star is 2.00 x 1030kg. I know that: Work= 1/2 (final moment of inertia) (finalangular velocity)2 - 1/2 (initial moment of inertia)(initial angular velocity)2 Final Moment of Inertia= (2.00 x1030 kg * 1.00 x 104m) Initial Moment of Inertia= (2.00 x1030 kg * 1.00 x 108m) How do I find the intial andfinal angular velocities? Final Moment of Inertia= (2.00 x1030 kg * 1.00 x 104m) Initial Moment of Inertia= (2.00 x1030 kg * 1.00 x 108m) How do I find the intial andfinal angular velocities?

Explanation / Answer

Period of rotation of a star after collapse                  T2 = (42r32 / GM ) Where M = mass of Earth            r2 = 1.00 x 104 m Work done by gravity = 1/2 (final moment of inertia) (finalangular velocity)2 - 1/2 (initial moment of inertia)(initial angular velocity)2 Where        1 =2 / T1        2 =2 / T2        T1 = (42r31 / GM )        T1 = (42r31 / GM )

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.