About 71 percent<span> of the Earth's surface is water-covered, and the oceans hold about </span>96.5 percent<span>of all Earth's water. Water also exists in the air as water vapor, in rivers and lakes, in icecaps and glaciers, in the ground as soil moisture and in aquifers</span>
We need to assume that the orbits are circular; this is a very good approximation and do not hesitate to adopt it. We need then to consider the basic equation of circular motion that relates centripetal acceleration, angular velocity, mass, radius and force:
. We also have the basic equation of Newton, F=ma. By checking, we see that for each planet we have that a=v^2*r where v is the angular velocity. v=
where T is the orbital period, hence we have that a=
. Denote with the index 1 the Earth case and with 2 the Mars case. We have then that
. Substituting the known values in a calculator, we get the result: the centripetal acceleration of earth is 2.32 times greater than that of Mars.
North to south (opposites attract ;) )
In the European part of Russia, the most productive land is in the Central Chernozem Economic Region and the Volga Economic Region, which occupy the grasslands between Ukraine and Kazakstan. More than 65 percent of the land in those regions is devoted to agriculture.