Answer: is constant
Explanation:
In order to analyze the velocity of the stars within a galaxy, the <u>galaxy rotation curves</u> (developed by the American astronomer Vera Rubin) are used. These graphs are elaborated as a scatter diagram in which the orbital velocity of the stars present in a galaxy is represented on the Y axis and the distance of these stars to the center of the galaxy on the X axis.
Thanks to this diagram, it has been possible to observe a characteristic behavior in the rotation speed of the stars (and gas) present in the galaxies, which differs from the rules of the orbital movement of the planetary systems postulated by Newton and Kepler.
This means that in these galaxy rotation curves it has been observed that the rotation speed of stars and gas is "constant", regardless of the distance to the center of the galaxy. This discrepancy and these results were then used to demonstrate the existence of dark matter in the universe.
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Industrialization occurs when machines and industry are introduced and occur on a large scale.
The U.S. federal system consits of a national government and what other government level
regional level
<h2>
Russia has the lowest population density in Eastern Europe.</h2><h2 />
Explanation:
Russia is the country with negative growth rate. The estimated population of 2020, is 145.93 million. At present, it ranks the 9th populated country. The largest city in Russia is Moscow with a population of 12.1 million people.
Due to the harsh climate, Russia is the most sparsely populated countries throughout the world. Russia is an urban country as 74% of Russians live either in towns or in cities.
Recently, the population has increased rapidly as people shifted from the remote areas to cities for better opportunities.
