Conservation of momentum
if an object with a given momentum breaks into two pieces, what constrains the velocities of the two pieces?
a) conservation of mass
b) conservation of velocity
c) conservation of kinetic energy
d) conservation of momentum
its due tomorrow, me

That's a good one, and there's more to this than meets the eye.

Mass and velocity don't have to be conserved, but energy and
momentum both do !

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 -

Alinear relationship would look like a straight line on the graph. it could have a positive negative or 0 slope. so it could be a line potentially going in any direction but it must be perfectly straight.