Question

Part II. Questions 1. What would be Sun's rotation period if it collapsed to a radius of 6000 km? How would the Sun's density change? (HINT: Conserve angular momentum. The moment of inertia of sphere is 0.4MR. 2. A star reaches "break-up” speed when it rotates so rapidly that the centrifugal acceleration at its equator equals the surface gravity (g). Estimate the rotation period of a typical white dwarf rotating at break-up speed. Assume the star remains spherical. (HINT: See Homework #15 about asteroids.)

answer should be 3 minutes for the first one and 10 seconds for the second one...how?

Answer 1

Radius of sun R, = 696340km new radius R₂ = 6000km From Law of conservation of corgular momentum, I, W = I₂ W2 Oo4 HR, W, = 0.4 MR² Wz R, 2W, = R₂2 w2 R, 211 = R 2T T2 = T, R2 T2 LT" (1: R₂ < R.) & Rotahonal period is decreases. ③ Initial density Pi = massy volume final density f = H UTR3 VAR ut R3 Change in density AP= Ps - Pi= 39 - 34 - YAR YTRB Density and is increases since radius is decreases. a 3M 3M 1m OO REDMI NOTE 8 PRO AI QUAD CAMERA