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# How to solve this problem?

Discussion in 'Physics' started by asdf arfw, Feb 20, 2018.

1. ### asdf arfw Thread Starter Member

Sep 9, 2017
43
0
I found this question on some Japanese TVshow and I could not figured out.
Find the radius of this black holes. when G= 6.67*10^-11 m^3.kg^-1.s^-2 , c = 3*10^8 , black hole's mass = 4.20*10^40 kg
Can u find the answer with these information.

2. ### WBahn Moderator

Mar 31, 2012
24,564
7,701
They probably mean the radius of the event horizon, which is simply the radius at which the escape velocity is the speed of light.

3. ### MrChips Moderator

Oct 2, 2009
19,146
6,152
How do you solve this problem?

What problem?

Would it not be better to state the problem in the title in the first place?

Such as: Find the radius of this black hole

recklessrog likes this.
4. ### BillO Distinguished Member

Nov 24, 2008
992
139
The Swarztschild radius is calculated thusly:

Rs = 2GM/(C^2)