winter day,

It is a winter day, with an outdoor temperature of 10 F = -12.2 C. The air is fairly still, such that the heat transfer coefficient near your fingers is about 12 W/m2-K. Let’s say that your pinky has a diameter of 1.3 cm and a length of 6 cm. Assume that your fingers act as fins, with a base temperature of 98.6 F = 37 C. Also assume – just for this problem – that the blood flow within them is slow, and that your fingers act as fins with a conductivity equal to that of water. Your pinky finger has a finite length, but we can approximate it as having no heat loss at the tip. Estimate the tip temperature of your pinky finger, in the absence of gloves. a) 36 C b) 10 C c) 4.7 C d) 9.6 C e) -11 C