1. The problem statement, all variables and given/known data Suppose that a 15 M(solar masses) star finally runs out of nuclear fuel in its core and undergoes a Type II supernova explosion. You are going to analyse the energy budget, calculating all the quantities in Joules. a) Estimate the amount of gravitational energy that would be liberated by the collapse of the core (say) 1.4 M(solar masses) to the size of neutron star. 2. Relevant equations PE = - GM/r 3. The attempt at a solution To calculate the gravitational PE. I believe the correct formula would be PE = -GM/r With: M = (15-1.4)M(solar masses) I'm not given the radius. Since it's a type II supernova, the radius would be around 10-15km. Is there a way I can accurately calculate the radius? Or since the question is asking for an estimate do I take an estimated radius based on it been a type II supernova, so a midpoint between 10-15km? Any help guidance very welcome.