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.
The correct answer is “D”
B.rely on wind power rather than electricity
Answer: Economists view the term Economic stability as a state of constant economic growth along with low inflation.
Explanation: When economy of any country is growing positively it ultimately reduces the inflation in a country. Thus we can say that they are inversely proportional to each other, means when you see increasing inflation, it indicates that the economic growth is either negative or stagnated however, when inflation is decreasing it indicates that the economy of a country is growing positively.
Natural resource management is a discipline in the management of natural resources<span> such as land, water, soil, plants and animals, with a particular focus on how management affects the quality of life for both present and future generations.Hence sustainable development can be followed where there is a judicial use of the natural resource.</span>
