Atrain rolls past a stationary observer. to him, the train is moving at a speed of 23 m/s west, and a woman on the train is moving at a speed of 22.4 m/s west. how long does it take the woman to move 13 m relative to the train?

Woman's velocity relative to train (23 m/s - 22.4 m/s) = 0.6 m/s
Distance woman wants to travel = 13m
To find how long she will take to move 13m relative to the train, take the distance she wants to travel divided by her velocity relative to the train.

(13m)/(0.6 m/s) = 21.6667 seconds or 21.7 seconds. 

Therefore, it will take the woman 21.7 seconds to move 13m.

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 -