Consider a poor lost soul walking at 5 km/h on a hot day in the desert, wearing only a bathing suit. This person's skin temperature tends to rise due to four mechanisms: (i) energy is generated by metabolic reactions in the body at a rate of 270 W , and almost all of this energy is converted to heat that flows to the skin; (ii) heat is delivered to the skin by convection from the outside air at a rate equal to k′Askin(Tair−Tskin), where k′ is 54 J/h⋅∘C⋅m^2, the exposed skin area Askin is 1.5 m2, the air temperature Tair is 50 ∘C , and the skin temperature Tskin is 36 ∘C; (iii) the skin absorbs radiant energy from the sun at a rate of 1400W/m^2; (iv) the skin absorbs radiant energy from the environment, which has temperature 50 ∘C .

Suppose instead the person is protected by light-colored clothing (e≈0) so that the exposed skin area is only 0.550 m^2 . What rate of perspiration is required now?