On average,what speed does a super giant star collapse as it goes supernova???

Question

Thanks for the extra detail....Tom Science 4

Answer 1

The surface of the iron core collapses at 0.25 c (one quarter the speed of light). This is the maximum speed. You want the average.

At the start of the collapse, the radius of the core is approximately 6000 km (depends on the overall mass of the star). After one second, the radius is approximately 50 km. The collapse of the iron core does not last much longer than one second.

Therefore, average speed (during that second) is 5950 km/s.