Internal energy physics OCR Unit 4 - thermal physicsWatch
also why does the speed of the whole body have no contribution to the internal energy?
surely if the body is moving faster then a rise in temperature has occurred and therefore there is a gain in internal energy?
With regard to the second half, temperature is really a measure of internal energy, that is, the energy of all the particles within the substance. This is a microscopic energy, and doesn't depend on macroscopic factors, like the entire body moving. Think about a moving object: at rest, the particles of the object vibrate with a certain energy. If you apply an external force to the body, it will move relative to its surroundings, but the energy of the constituent particles remains pretty much the same. A change in kinetic and potential energy of the entire body doesn't translate to a change in the energy of its particles