Astronomy quiz question: mass, densities, and event horizons

Astronomy 10 Quiz 10, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q10.1

[3.0 points.] Which one of the following choices best explains why a black hole is the only object that can have an event horizon?
(A) It has zero density.
(B) It has infinite mass.
(C) It has zero size.
(D) It has infinite energy.
(E) It can distort spacetime.

Correct answer: (C)

Section 4160
(A) : 5 students
(B) : 7 students
(C) : 15 students
(D) : 1 students
(E) : 2 students

Section 5166
(A) : 6 students
(B) : 16 students
(C) : 11 students
(D) : 3 students
(E) : 5 students

Previous posts:
Astronomy clicker question: masses, densities, and event horizons.
Astronomy in-class activity: masses, densities, and escape velocities.