beginning with m, end with olecules. molecules. especially h2o molecules 'cause water molecules tend to stick to each other. they do that by electrical forces, something we'll be talking about soon. but there's a tendency for water molecules to stick. you know why the water molecules in this room right now don't condense all over the place? 'cause it's moving more than 15,000 kilometers per hour. and these things are hit-- bounding off so fast. they go--they stay in the paper. but if you slow 'em down, they'll condense. so let's get back to lee's question. here we have a couple of molecules, kinetic energy another molecule. let's suppose it's h2o. kinetic energy moving toward each other. add these two kinetic energies, you get a particular value. can these energies transfer? i mean, if i have a couple of pool balls, can i have one pool ball come in--boom--slow down, this one speeds up? and the energy before and the energies after are always the same? guess what behaves the same way, begin with olecule-- begins with m. molecules, ok