A galaxy is observed receding from Earth with a speed of 2800 km/s
If the Hubble constant is 22 km/s per million light-years, estimate how many years ago the light that we presently see from the galaxy actually left the galaxy. (c = 3.00 × 108 m/s, 1 ly = 9.461 × 1015 m, 1 y = 3.156 × 107 s)
A) 1.4 × 107 y B) 4.2 × 107 y C) 4.2 × 108 y D) 4.2 × 106 y E) 1.3 × 108 y
E
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A 2.50 A current is carried by a copper wire of radius 1.0 mm. If the density of conduction electrons is 
what is the drift velocity of the conduction electrons?
A. 
B. 
C. 
D. 
E. 
The planet Jupiter is about 300 times as massive as Earth, yet on its surface you would weigh only about 3 times as much because
A) your mass is 100 times less on Jupiter. B) Jupiter is significantly farther from the Sun. C) Jupiter's radius is 10 times Earth's radius. D) you are 100 times more weightless there. E) none of the above
Harlow Shapley used observations of globular clusters to determine the position of the center of the galaxy
a. True b. False Indicate whether the statement is true or false
Which of the following is a solution to the wave equation, 
?
A.
B.
C.
D.
E.