Assuming the Hubble constant is (21 km/s)/(106 ly), what is the recession speed of a galaxy 300 million parsecs away? (1 parsec = 3.26 ly)
a. 4200 km/s
c. 640 km/s
b. 21,000 km/s
d. 7000 km/s
B
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Suppose you could float in space just a few meters above Saturn's rings. What would you see as you looked down on the rings?
A) countless icy particles, ranging in size from dust grains to large boulders B) a solid, shiny surface, looking much like a piece of a Blu-ray disk or DVD (or vinyl record album) but a lot bigger C) dozens of large "moonlets" made of metal and rock, each a few kilometers across D) long, solid strings of matter, each distinct from the next
How can you identify an asteroid in a long exposure taken of stars through a telescope? (Assume the telescope is tracking the sky with Earth's rotation, so that stars appear as points of light.)
A) The asteroid will be much brighter than the surrounding stars. B) The asteroid will be much dimmer than the surrounding stars. C) The asteroid will appear as a streak because of its motion relative to the stars. D) The asteroid will have a noticeable circular disk, rather than being just a point of light like the stars. E) The asteroid will be recognizable by its long, fuzzy tail.
A ball is thrown straight up. It reaches its highest point and then falls back. Which of the following is the correct statement?
A. Throughout its motion, the ball's acceleration is zero B. At the highest point in its motion, the ball's acceleration is zero C. At the highest point in its motion, the ball's velocity and acceleration are zero D. At the highest point in its motion, the ball's velocity is zero E. Throughout its motion, the ball's velocity is zero
Heavy nuclei are unstable because
a. each nucleon is a separate particle that is not acted on by the nuclear force. b. there are not enough protons present relative to the number of neutrons for the electrical force to be strong enough. c. the nuclear force dominates the Coulomb repulsive force at distances less than 2 fm, but falls off rapidly at greater distances. d. nuclei are stable only when the number of neutrons equals the number of protons. e. nuclei are stable only when the number of protons exceeds the number of neutrons.