2. A sky diver jumps from a plane at an altitude of 20km, where the temperature is around -20 C. After an initial acceleration period (which you can ignore), they fall through the air at a constant speed of 195 km/h or 54 m/s (this is the terminal velocity you reach as a result of air friction). (a) If you assume a 'typical' person (75kg mass, surface area 1.8m, skin temperature 34C) without any special protective clothing, make a rough estimate of how much heat the sky diver loses (per unit time) as a result of the extreme air convection that they experience during their fall. (Please note that the relevant equation is technically only valid for velocities up to around 20m/s, but please ignore this limitation for the moment). (b) (c) If you assume a BMR of about 100W for this person, what is their net heat loss in free fall (in W)? If you assume that the sky diver will deploy their parachute at about 500m from ground, how much time do they spend in the free fall phase? Given their net heat loss from part b, by how much would their body temperature drop during this time, assuming the specific heat of the body to be 3,470 J/(kg.K)? Is this cause for concern, i.e. would you recommend special protective clothing?