During its evolution, a star of 1 solar mass (the mass of our Sun) expands to 4.

Question

During its evolution, a star of 1 solar mass (the mass of our Sun) expands to 4.18 times its original radius. Assume that, during this expansion: - the star has no appreciable loss of mass - the mass is uniformly distributed through the volume - the star remains spherical during the entire process a) If the star was initially spinning with a period of To = 34.7 days: find Tf, the period of rotation of the star after the expansion days b) Calculate the ratio R., where R = (final kinetic energy of the star)/(initial kinetic energy of the star) NOTE: You may assume there is no translational motion.

Explanation / Answer

Onservation of angular momentum states that I1 ?1 = I2 ?2 I1 = mr2 I2 = m(4.18r)2 Also, ? = 2p/T So, T2 = T1(4.18)2 =34.7 x 4.182 = 606.3 days Kinetic Energy =1/2 I?2 But I? is constant SO, ratio of KE is nothing but ?1/?2 = T2/T1 = 4.182 = 17.47 ?R = 17.47 therefore, ratio R = 17.47

Related Questions

Navigate

• Browse (All)
• Browse D
• Subjects

---

---

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