The black hole in the galaxy M82 has a mass about 500 times the mass of our Sun. It has about the same volume as Earth's moon. What is the density of this black hole?
mass_sun = 1.9891 x 10^30 kg
volume_moon = 2.1968 x 10^10 km^3
(b) The circumference of the earth is 25,000 mi at the equator. What is the circumference in kilometers? 40200 km. Check the number of significant figures.
What is the circumference in meters? 40200000 m. Check the number of significant figures.