Each Voyager spacecraft carries a "postcard" designed to be understandable to any aliens that might someday encounter it. On the "postcard," scientists pinpointed the location of Earth by triangulating it between pulsars
Why did the scientists choose pulsars rather than some other type of star? A) Pulsars are very bright and therefore easy to find.
B) Several pulsars are located within a dozen light-years of our solar system, making them useful for finding our solar system.
C) We're pretty sure that aliens will have only radio telescopes and not optical telescopes, so they'll have a better chance of seeing pulsars than ordinary stars.
D) Pulsars are easy to identify by their almost perfectly steady periods of pulsation.
D
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When an unstable nucleus decays by emitting an alpha particle, the atomic number Z of the nucleus
A) increases by 4. B) increases by 2. C) decreases by 2. D) decreases by 4. E) remains unchanged.
A fast-moving body must have a larger acceleration than a slow-moving body
Indicate whether the statement is true or false
The climate of northwestern Europe is greatly affected by the
A) Kuroshio current. B) Gulf Stream. C) trade winds. D) jet stream.
What is the angular separation of the two second-order spectral lines having wavelengths 417 nm and 388 nm using a diffraction grating having 456 lines/mm?
A) 1.63° B) 1.52° C) 0.815° D) 3.26°