Discuss the application of the first law of thermodynamics to a mountaineer who eats food, gets warm and perspires a lot during a climb, and does a lot of mechanical work in raising herself to the summit. The mountaineer also gets warm during the descent. Is the source of this energy the same as the source during the ascent?
Solution 5DQ Step 1 : Let us consider the first law of thermodynamics, it is a law of conservation of energy , which says the total energy of an isolated system is constant, Energy can neither be created and nor be destroyed. From the first law of thermodynamics, Q = W + U , where Qis the heat supplied to a system, W is the work done by the system and U is the change in internal energy of the system. Now, U = Q W , this means that the change in internal energy is influenced by heat supplied to the system and the work done by the system. In case of the mountaineer, the mechanical work done by mountaineer gets converted into to internal heat energy, which causes the mountaineer to feel warm while descending While he is ascending, the mechanical work done and the food he takes acts as the source of energy which also causes to increase the internal energy of the climber and thus he feels more heat and warmer while climbing the mountain, as ascending takes more mechanical energy
