Author Question: It is more difficult to determine the total amount of dark matter in an elliptical galaxy than in a ... (Read 17 times)

Melani1276 · **on:** Jul 27, 2018

It is more difficult to determine the total amount of dark matter in an elliptical galaxy than in a spiral galaxy. Why?

A) Elliptical galaxies lack the atomic hydrogen gas that we use to determine orbital speeds at great distances from the centers of spiral galaxies.
B) Elliptical galaxies contain much less dark matter than spiral galaxies, so it's much more difficult to measure.
C) Stars in elliptical galaxies are dimmer, making them harder to study.
D) cannot observe spectral lines for elliptical galaxies.

Question 2

Which of the following is not one of, nor follows directly from, Kepler's laws?

A) The orbit of each planet about the Sun is an ellipse with the Sun at one focus.
B) As a planet moves around its orbit, it sweeps out equal areas in equal times.
C) The force of attraction between any two objects decreases with the square of the distance between their centers.
D) A planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun.
E) More distant planets move at slower speeds.