The wind blows around the sand so no one grain of sand stays in the same place forever. The winds molds the sand dunes for a very short time
Answer:
Explanation:Egypt, country located in the northeastern corner of Africa. Egypt’s heartland, the Nile River valley and delta, was the home of one of the principal civilizations of the ancient Middle East and, like Mesopotamia farther east, was the site of one of the world’s earliest urban and literate societies. Pharaonic Egypt thrived for some 3,000 years through a series of native dynasties that were interspersed with brief periods of foreign rule. After Alexander the Great conquered the region in 323 BCE, urban Egypt became an integral part of the Hellenistic world. Under the Greek Ptolemaic dynasty, an advanced literate society thrived in the city of Alexandria, but what is now Egypt was conquered by the Romans in 30 BCE. It remained part of the Roman Republic and Empire and then part of Rome’s successor state, the Byzantine Empire, until its conquest by Arab Muslim armies in 639–642 CE.
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 given information is expressed in ratio. However, a ratio is basically a fraction. So, 4:10 is just equal to 4/10 or 2/5 in simplified terms. Similarly, 12:20 is just equal to 12/20 or 6/5 in simplified terms. The smaller ratio is 2/5 because the numerator is less than the denominator. So, it follows that the answer is less than 1. The other ratio has a much greater numerator. So, we would expect that that would be greater than 1.
Answer:
It's the big flat continent at the bottom.
