Could someone help me start this problem. My mind it in the angular momentum mode and I am having trouble seeing where to start on this one. The sun's radius is 6.96E8m and it rotates with a period of 25.3d. Estimate the new period of rotation of the sun if it collapses with no loss of mass to become a neutron star of radius 5.5km. Give the result in seconds. Thank you very much!