Niagara falls is a set of very large waterfalls located on the border between new york and ontario, canada. over 200,000 cubic feet of fast-moving water falls approximately 180 feet every second. water at the top of the falls possesses kinetic energy and gravitational potential energy. only gravitational potential energy. only kinetic energy. neither gravitational potential energy nor kinetic energy.

The first choice is correct.  It has both.

-- It has kinetic energy because it's "fast-moving" water.

-- It has gravitational potential energy because it's hundreds of feet
above the riverbed that it's getting ready to fall down to, as soon as
it goes over the edge.

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 -

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