8. Centripetal Forces & Gravitation

Which of the following statements about black holes is not true?

In the context of black holes, what is meant by the singularity of a black hole?

Viewed from a distance, how would a flashing red light appear as it fell into a black hole?

If the Sun were compressed to its $r$_s (Schwarzschild radius), what would happen to it?

A black hole is most likely to form as the final stage of stellar evolution for which type of main-sequence star?

Which of the following occurs before a black hole forms?

Which process leads to the formation of a black hole from a massive star?

As a flashing red light falls into a black hole, how would its appearance change to a distant observer?

Star A is $5$ times hotter than Star B. According to the $Stefan-Boltzmann$ law, how many times brighter is Star A than Star B, assuming they have the same size?

Astronomers have found a small, but incredibly massive object at the center of our Milky Way galaxy, and suspect it is a black hole. A cloud of gas orbits this object at $1.8\times 10^5$ m/s every 78,500 years.

a) What is the mass of this alleged black hole?

b) How large is this black hole?

(II) Astronomers using the Hubble Space Telescope deduced the presence of an extremely massive core in the distant galaxy M87, so dense that it could be a black hole (from which no light escapes). They did this by measuring the speed of gas clouds orbiting the core to be 780 km/s at a distance of 60 light-years ( = 5.7 x 10¹⁷ m) from the core. Deduce the mass of the core, and compare it to the mass of our Sun.