A horse whose mass is M gallops at constant speed v up a long hill whose vertical height is 11, taking an amount of time Ito reach the top. The horse's hooves do not slip on the rocky ground, so the work done by the force of the ground on the hooves is zero (no displacement of the force). When the horse started running, its temperature rose quickly to a point at which from then on, heat transferred from the horse to the air keeps the horse's temperature constant. (b) Next consider the Universe as the system of interest. Write out the Energy Principle for this system. Remember that terms on the left hand side should include all energy changes for the system, while the terms on the right hand side shold relate to the surroundings. Which of the following terms are equal to O? AEchemical AU grav O AE thermal, horse O A(mc2 ) O AK AEthermal, air OW