Sunspots are dark splotches on the Sun. Which statement is true?
A) They are hotter than the surrounding areas of the Sun.
B) They are extremely cold objects, as cold as Pluto.
C) They are extremely hot, but cooler than the surrounding areas of the Sun.
D) They are solid bodies floating on the surface of the Sun.
E) They are associated with areas of very low magnetic fields.
C
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From Earth, one satellite appears to overtake another. The faster satellite is
A) higher. B) lower. C) smaller. D) can't say
When we look at an object that is 1,000 light-years away we see it
A) as it was 1,000 years ago. B) as it was 1,000 light-years ago. C) as it is right now, but it appears 1,000 times dimmer. D) looking just the same as our ancestors would have seen it 1,000 years ago.
Two point charges of +1.0 ?C and -2.0 ?C are located 0.50 m apart
What is the minimum amount of work needed to move the charges apart to double the distance between them? (k = 1/4??0 = 8.99 × 109 N ? m2/C2) A) -36 mJ B) +18 mJ C) 0 mJ D) +36 mJ E) -18 mJ
How fast must a hydrogen atom be traveling for its kinetic energy to be just enough to excite the ground-state atom to its first excited state in a collision? (1 eV = 1.60 × 10-19 J, mH ? mproton = 1.67 × 10-27 kg)
A) 66.5 km/s B) 21.7 km/s C) 44.2 km/s D) 113 km/s E) 51.0 km/s