A star of spectral type O lives approximately how long on the main sequence?
A) 1,000 years
B) 10,000 years
C) 10 million years
D) 100 million years
E) 1 billion years
C
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A race car circles 10 times around an 8-km track in 20 min. What is its average speed per lap?
What will be an ideal response?
An ideal Carnot air conditioner operates between an indoor temperature of 20°C and an outdoor temperature of 39°C. How much energy does it use to remove 2000 J of thermal energy from the interior of the house?
A) 105 J B) 130 J C) 780 J D) 520 J E) 340 J
A bar magnet passes through a circular loop of wire as shown below. At the instant that the middle of the magnet passes through the loop, the induced current ( as seen from the coil # 2) is
A. ccw and increasing.
B. cw and decreasing.
C. cw and increasing.
D. zero.
Due to increasing amounts of terrestrial radio noise, in the future SETI telescopes may be placed
A) on the tops of tall mountains B) in near-Earth orbit C) on the far side of the Moon D) in remote desert locations