One cross-country skier is wearing a down jacket that is 2.0 cm thick. The thermal conductivity of goose down is 0.025 W/(m∙K). Her companion on the ski outing is wearing a wool jacket that is 0.50 cm thick. The thermal conductivity of wool is 0.040 W/(m∙K).
(a) If both jackets have the same surface area and the skiers both have the same body temperature, which one will stay warmer longer?
(b) How much longer can the person with the warmer jacket stay outside for the same amount of heat loss?