Do microwaves make polar molecules spin or vibrate? I’ve been reading about how microwave ovens heat up your food and I keep finding conflicting answers (some say it vibrates, others say it spins). On the one hand, I’ve also read that heat is the molecules kinetic energy making them collide and bounce off other molecules and, if that is the case, I can’t see how spinning the molecule would cause the molecule to go shooting off in a certain direction since spinning doesn’t move anything until there is something to push off of. On the other hand, it doesn’t make sense for an oscillating magnetic wave to push any real direction since the negative side of the wave would just pull it right back and cancel out any kinetic energy the molecule received, making little to no progress. What am I missing?
 A: rotating molecules will certainly cause heating (as also vibrating molecules). the molecules are not in isolation, but are embedded in the matter which is the rest of the food. this "embedding" is done by some forces, which in case of water, a highly polarized molecule, is depending on the orientation of the molecule, as the positive part of foodstuff molecules will be closer to the negative part of the water molecules (the oxygen atom) and the negative part of the foodstuff molecules will be closer to the positive part of the water molecules (the hydrogen atoms). as a side note, this is how water solutions work. back to the microwave: when water molecules move, either spinning or vibrating, the distances between their positive and negative parts and the respective negative and positive parts of the foodstuff molecules change, therefore they exert force on the foodstuff molecules, that "feel the urge" to rearrange themselves such that their orientation and distance will adjust the new orientation (or "stretching") of the water molecules. this movement propagates through the foodstuff matter and it heats up the food
