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This is College Physics Answers
with Shaun Dychko.
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We are going to calculate the
size of a black hole
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that has the mass of the Earth.
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So the Schwarzschild radius
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from equation 2 in chapter 34
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it's 2 times the gravitational constant times
the mass divided by *c* squared.
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So this is the distance to
the event horizon
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around the black hole
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and so that's gonna be 2 times 6.67 times
10 to the minus 11
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newton meter squared per kilogram squared
times mass of the Earth
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divided by the speed of light squared
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giving a radius of 8.86 millimeters.