Two balls, each with a mass of 0.844 kg, exert a gravitational force of 8.45 × 10−11 non each other. how far apart are the balls? the value of the universal gravitational constant is 6.673 × 10−11 n m2/kg2.

The Universal Gravitation law is F=GMm/d^2
So: 8.45x10^-11=6,673x10^-11x0,844x0,844/d^2
d^2=1,78, so finale d=1,33m

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 -