Assume the horse’s hooves do not slip on the rocky ground and that air resistance is negligible. 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. Once the temperature of the horse is constant, which equation is the correct statement of the energy principle, ∆Esys = W +Q, taking the horse as the system?
1.∆Erest+∆K+∆Echemical+∆Ethermal+∆U grav=−Mgh−|Q|
2.∆Echemical+∆Ethermal= 0