What is a Cepheid variable?
A) It is a type of luminous star that makes an excellent standard candle.
B) It is a bright source of variable x-ray emission, thought to harbor a supermassive black hole.
C) It is a main-sequence star of spectral type B5.
D) It is a type of galaxy that varies in its light output.
A) It is a type of luminous star that makes an excellent standard candle.
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A boat moves at 10.0 m/s relative to the water. If the boat is in a river where the current is 2.0 m/s, how long does it take the boat to make a complete round trip of 1.00 km upstream followed by a 1.00 km trip downstream?
At which is the potential smallest?
A. A B. B C. C D. D E. E F. None of the labeled points
Suppose you live at latitude 40°N. What is the altitude and direction of the North Celestial Pole in your local sky?
A) 50°, due north B) 40°, due north C) It is on your zenith. D) It is on your horizon, due north. E) 50°, due south
When an object reaches its terminal speed, its acceleration is zero
Indicate whether the statement is true or false