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 Special and General Relativity Special and General Relativity Physics Help Forum Oct 4th 2018, 01:57 PM #1 Junior Member   Join Date: Sep 2018 Posts: 7 Density of Black Hole So when I tested the sample question I got the right answer. But doing a practice one I feel like I got the wrong answer - it seems way too high: Black hole mass - 4.31 x 10^6 I calculated Rs to be = 1.27 x 10^7 Average density: P = m/v m = (4.31x10^6) x (1.989x10^30) m = 8.57x10^36 km v=4/3 x π x r^3 v= 4.3 x π x (4.127x10^7)^3 v= 8.22 x 10^21 P = (8.57x10^26) / (8.22 x 10^21) P = 1.04 x 10^15 km m^-3 Have I calculated this correctly or have I done something wrong? When I go on to look a Roche Limit: 1400 kg m^-1 = Sun's average density r = 2.456(((1.04x10^15)/(1400))^1/3) r = 2243.17 Which seems way too high?  Tags black, density, hole Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post pittsburghjoe Philosophy of Physics 5 May 21st 2019 07:31 PM philipishin Special and General Relativity 2 Nov 14th 2015 01:39 PM kiwiheretic Nuclear and Particle Physics 3 Jun 21st 2014 11:53 PM jaiii Theoretical Physics 1 Feb 2nd 2011 09:17 AM poonam sandhu Nuclear and Particle Physics 0 Jan 20th 2010 01:57 AM