Satellites feel the gravitational pull of the earth. They remain in orbit because of their velocity, which acts to counteract gravity. (The satellite wants to fly out in a straight line, but gravity forces it to curve towards the earth.) Consider a communications satellite that needs to be 41000 km above the Earth's surface.

(a) Assuming the satellite travels in a perfect circle, what is the radius of the satellite's travel. (The radius of the earth is 6375 km.)?

(b) At the satellite's altitude, the acceleration of gravity is 0.177 m/s2. What is the magnitude of the tangential velocity that the satellite must have to remain in orbit?

c) How much time will the satellite take to orbit the earth?

An  atom  (ours, not carroll's) consists of a positively charged  nucleus, surrounded by one or more negatively charged particles called  electrons. the positive charges equal the negative charges, so the atom has no overall charge; it is electrically neutral. most of an atom's mass is in its nucleus; the mass of an electron is only 1/1836 the mass of the lightest nucleus, that of hydrogen. although the nucleus is heavy, it is quite small compared with the overall size of an atom. the radius of a typical atom is around 0.1 to 0.25 nanometres (nm), whereas the radius of a nucleus is about 10-6  nm.  *  if an atom were enlarged to the size of the earth, its nucleus would be only 200 feet in diameter and could easily rest inside a small football stadium.read more on -

Rain is pulled by gravity which is a non contact force