A telescope performs best:
A) on a high mountaintop where the air is thin and steady.
B) in a valley where the air is calm.
C) on a hill close to the ocean where the atmospheric turbulence is high.
D) close to a valley where the seeing is poor.
A
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A 2-kg rifle is horizontally suspended by a pair of strings so that recoil can be measured. The rifle fires a 0.001-kg bullet at a speed of 200 m/s. The recoil velocity of the rifle is about
A) 0.001 m/s. B) 0.01 m/s. C) 0.1 m/s. D) 1 m/s. E) none of the above
The air pressure is 14.8 lb/in2
a. What is the approximate height, in centimeters, of a mercury column that this pressure would support? b. What would be the height, in meters, of the column for a water barometer?
The best answer to both the flatness and horizon problems is:
A) the Steady State Theory. B) the GUT theory. C) the inflationary epoch. D) dark energy. E) decoupling.
A scientist claims that all red main-sequence stars are 1 billion years old. Which of the following, if true, would prove that this claim is false?
A) The discovery of a red main-sequence star in a star cluster where the main sequence turnoff is about that of the Sun B) The discovery of a red main-sequence star in a star cluster where all the other stars are red giants or red supergiants C) Stellar evolution theory predicts that the main-sequence lifetime of red stars can be as long as 100 billion years. D) The minimum lifespan of a red main-sequence star is estimated to be 10 billion years.