Humans are able to control their heat production rate and heat loss rate to maintain a nearly constant core temperature of Tc
37 C under a wide range of environmental conditions. This process is called thermoregulation. From the perspective of calculating heat transfer between a human body and its surroundings, we focus on a layer of skin and fat, with its outer surface exposed to the environment and its inner surface at a temperature slightly less than the core temperature, Ti
35 C
308 K. Consider a person with a skin/fat layer of thickness L
3 mm and effective thermal conductivity k
0.3 W/m
K. The person has a surface area A
1.8 m2 and is dressed in a bathing suit. The emissivity of the skin is 
0.95. 1. When the person is in still air at T

297 K, what is the skin surface temperature and rate of heat loss to the environment? Convection heat transfer to the air is characterized by a free convection coefficient of h
2 W/m2
K. 2. When the person is in water at T

297 K, what is the skin surface temperature and heat loss rate? Heat transfer to the water is characterized by a convection coefficient of h
200 W/m2
K.