In thinking about specific heat, I have been unable to resolve a particular issue. If molecules in a substance are bumped and move faster, then they will measue to be at a temperature proportional to the speed they are moving which is a consequence of how hard on average they were hit(heat energy). The law of conservation of energy suggests (to a very simple mind) that all substances of equal mass will require the same amount of energy to increase in temperature by a specific amount. I know this is not true. I also know that molecules can vibrate internally (the atoms in a molecule jiggle relative to each other). I think i have heard this referred to as degrees of freedom. THE QUESTION: Why wouldn't the internal vibrations contribute to temperature? Wouldn't the vibrating atoms of a molecule in their oscillations bump out and hit other molecules and speed them up, thus making the temperature read at what would be expected to a lay person. Is this really what causes varying specific heat capacities? If so, what is restricitng the internal vibrations from contributing to the temperature reading of the substance?