What was the temperature of the universe when the recombination took place that produced the cosmic background radiation we observe today?
a. about 2.7 K
b. about 300 K
c. about 3000 K
d. about 3 million K
e. about 3 billion K
C
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Evaluate the Reynolds number for flow over a tube from the following data
GIVEN
FIND
The Reynolds Number (Re)
Two radio antennas are 10 km apart on a north-south axis on high mountain tops at the seacoast. The antennas broadcast identical AM radio signals, in phase, at a frequency of 4.70 MHz
A steamship, 200 km offshore, travels toward the north at 15 km/h and passes east of the antennas. A radio on board the ship is tuned to the broadcast frequency. The reception of the radio signal on the ship is a maximum at a given instant. How much later until the next occurrence of maximum reception? (c = 3.00 × 108 m/s) A) 5.1 min B) 3.8 min C) 6.4 min D) 7.7 min E) 8.9 min
What is the characteristic color of a reflection nebula?
A. yellow B. green C. black D. red E. blue
The discovery of Charon allowed astronomers to determine Pluto's mass
Indicate whether the statement is true or false