A syste m does 125 J of work on its environment and gains 88.9 J of heat in the process. Find the change in the internal energy of (a) the system and (b) the evironment. (a) number                                       units (b) number                                       units

A diesel engine has efficiency 0.180. (a) In order for this engine to do 1.24 * 10^4 J of work, how many joules of heat must it take in? (b) How many joules of this heat is discarded?

Heat engines take input energy in the form of heat, use some of that energy to do work, and exhaust the remainder. Similarly, a person can be viewed as a heat engine that takes an input of internal energy, uses some of it to do work, and gives off the rest as heat. Suppose a trained athlete can function as a heat engine with an efficiency of 0.16. (a) What is the magnitude of the internal energy that the athlete uses in order to do 1.7x104 J of work? (b) Determine the magnitude of the heat the athlete gives off.

1. Suppose a woman does 600 J of work and -9500 J of heat transfer occurs into the environment in the process. (a) What is the decrease in her internal energy, assuming no change in temperature or consumption of food? (That is, there is no other energy transfer.) J AE int (b) The internal energy is stored energy due to food intake. Treating the change in internal energy as the input energy and work done as output, what is her efficiency? Efficiency, Eff: % (c) What physics law did you use in this problem? Zeroth Law of Thermodynamics First Law of Thermodynamics Second Law of Thermodynamics