Why was the globular cluster M13 selected as the target for the 1974 Arecibo message?
A) globular clusters are the most likely place to find stars with planetary systems
B) stars in globular clusters are rich in heavy elements, the building blocks of life
C) signals from advanced civilizations have previously been detected coming from this cluster
D) globular clusters are densely packed with stars, hence maximizing the probability of interception by an advanced civilization
D
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The supernova of 1054 AD produced
A) a remnant still visible to the naked eye, the Crab Nebula, M-1. B) a pulsar with a period of 33 milliseconds, visible optically. C) the closest known neutron star to our Sun. D) the most famous black hole. E) no remaining visible trace, as it was a type I supernova.
An 80.0 kg climber climbs to the top of Mount Everest, which has a peak height of 8848 m. What is the climber’s potential energy with respect to sea level?
A metal block has a mass of 5 grams and a volume of 1 cubic centimeter. A piece of the same kind of metal with a volume of 2 cubic centimeters has a density of
A) 2.5 g/cm3. B) 5 g/cm3. C) 10 g/cm3.
You are driving along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind and you perceive the frequency as 1310 Hz
You are relieved that he is in pursuit of a different speeder when he continues past you, but now you perceive the frequency as 1240 Hz. What is the frequency of the siren in the police car? The speed of sound in air is 343 m/s. A) 1300 Hz B) 1320 Hz C) 1270 Hz D) 1360 Hz E) 1370 Hz