Question

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?

Short answer

The source of heat is the same during both ascent and descent.

Step-by-step solution

Explanation

When the mountaineer ascends, the food he consumes is spent on heating himself, then on perspiring to keep his body temperature constant and on work done. When he descends, the situation is the same but he does less work because he doesn't have to completely negate the gravitational force but only to keep his descending speed in check so the source of this heat is the same.

Conclusion

Hence, the source of heat is the same during both ascent and descent.