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.
Potable Water is tested and treated industrially. Thus, Potable Water is expensive. Therefore, Access to potable water is very limited by money.
<h3 /><h3>What is potable water?</h3>
Potable water is the water, that is tested and safe for drinking and cooking arrangements. Water is tested and treated industrially.
Thus, Potable water is expensive.
Therefore, Access to Potable water is very limited by money.
To learn more about Potable water, refer:
brainly.com/question/26104890
11.86 Earth years or once every 4,330.6 Earth days
