Answer:
b. flat rotation curves in spiral galaxies
Explanation:
Dark matter accounts for majority of the matter in the universe (about 85%). It is considered to be composed of subatomic particles which are yet to be discovered. Dark matter cannot be observed because it does not emit light that can be detected. Only its gravitational effect is visible.
Astronomers when calculated the mass of the visible matter and tried to account for the observed speed of stars in the galaxy, there was a mismatch. To understand what caused this mismatch, astronomers gave name to the invisible matter as the Dark Matter.
The expected velocity of stars should decrease away from the near the center of the galaxy but a constant velocity of stars was observed that is a relatively flat rotation curve was obtained.
Thus, flat rotation curves in spiral galaxies in an evidence of Dark Matter.
Answer:
The European diseases affected the people of the Western Hemisphere greatly. Outbreaks of various diseases brought by the Europeans to the Americas such as smallpox, influenza, malaria, diphtheria, etc. It killed many of the Native Americans and disrupted their societies. Due to the diseases having been in Europe for a longer time, the people got more immune to them, however, this was the first time the Native Americans were exposed to it.
Due to them not being immune, the mortality rate for a Native American catching a disease was extremely high, much higher than they would have been if it was already introduced. The Native Americans also had very limited health care therefore were not able to be treated as well as the Europeans. Because of this, the diseases affected them for much longer periods of time.
Answer:
whne your like 30(i think) your not forced but some people still join bc there willing to sacerfice there life to help, if you 18-30 they can force you to join
Explanation:
A light year (186,00 miles). (300,000 kilometers per second)
