By studying distant galaxies in the 1920s, Hubble made which of the following important discoveries that led us to conclude that the universe is expanding?
A) All galaxies contain billions of stars, and all galaxies have spiral shapes.
B) All galaxies were born at the same time, and all will die at the same time.
C) All galaxies outside the Local Group are moving away from us, and the farther away they are, the faster they're going.
D) All galaxies outside the Local Group are orbiting the Local Group.
E) All galaxies outside the Local Group are moving away from us, and all are moving away at nearly the same speed.
C
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As you move farther away from a source emitting a pure tone, the frequency of the sound you hear decreases
Indicate whether the statement is true or false
A very thin uniform rod, 2.40 m long and of weight 135 N, has a frictionless hinge at its lower end. It starts out vertically from rest and falls, pivoting about the hinge
Just as it has rotated through an angle of 55.0°, what is the downward acceleration of the end farthest from the hinge? A) 5.02 m/s2 B) 8.03 m/s2 C) 9.80 m/s2 D) 12.0 m/s2 E) 19.6 m/s2
In the outer regions of the solar nebula where temperatures were low,
A) only rock and iron could condense B) only hydrogen compounds could condense as ices C) hydrogen and helium gases were able to condense D) in addition to rock and iron, hydrogen compounds also condensed as ices
In which eon of Earth's history did dinosaurs and mammals first appear?
A) Hadean B) Archean C) Phanerozoic D) Proterozoic