It is unlikely that we will be able to detect the signals from civilizations in other galaxies because
A) signals from other galaxies will be severely weakened by distance, making them far harder for us to detect
B) other galaxies are unlikely to harbor intelligent civilizations
C) signals from civilizations on other galaxies will not reach us before we give up listening
D) they will most likely transmit at wavelengths that will be absorbed by intergalactic gas
A
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The Kelvin temperature scale is based on the freezing point of water
a. True b. False Indicate whether the statement is true or false
Answer the following statement(s) true (T) or false (F)
1. At time t = 0 a person is sliding due east on a flat, frictionless plane of ice. The net force on this person is due to a battery-powered fan the person holds that exerts a southward thrust force on the person. Assuming that drag is negligible, the eastward component of the person’s velocity is unaffected by this force.
Beryl states that insulation with the smallest possible thermal conductivity is best to keep a house warm in winter, but worst for keeping a house cool in summer. Sapphire insists the reverse is true: low thermal conductivity is good in the summer, but bad in the winter. Which one, if either is correct?
a. Beryl, because low thermal conductivity results in low heat transfer. b. Beryl, because low thermal conductivity results in high heat transfer. c. Sapphire, because low thermal conductivity results in low heat transfer. d. Sapphire, because low thermal conductivity results in high heat transfer. e. Neither, because low heat transfer is desirable both in summer and in winter.
Exhibit 7-1
Three 5.0-kg masses are located at points in the xy plane as shown in the figure.
?
?
Use this exhibit to answer the following question(s).
Refer to . What is the magnitude of the resultant force (caused by the other two masses) on the mass at the origin?
a.
2.7 × 10?8 N
b.
2.1 × 10?8 N
c.
1.8 × 10?8 N
d.
2.4 × 10?8 N
e.
2.9 × 10?8 N