Calculate the proper time τ elapsed by the watch of an observer who falls radially in a Schwarzschild field starting from rest at r =
R > 2M until the person hits the singularity at r = 0. Show that τ is
given by τ =

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 -

Sound energy is produced when an object vibrates. examples are 1- a balloon popping2-a whistle3- a waterfall