Question

a) What is the rate of heat transfer (by conduction) through the 3.00 cm thick fur of an animal having 1.40 m² of surface area? The animal's skin temperature is 32.0 ˚C, and the air temperature is -5.00 ˚C, and assume fur has the same thermal conductivity as air.

b) What (additional) food intake would this animal need to consume in one day to offset this energy loss due to heat transfer, assuming the added food energy is converted with 30% efficiency? Report the final answer in Calories (1 Calorie = 4186 J)

Answer 1

Part - a

The rate of heat transferred by conduction is

by plugging the values we get

which gives us

or

This is the required rate of heat transferred by conduction

Part - b

The energy required from food is

by plugging all the values we get

which gives us

The efficiency is 30% , thus the total energy of food items will be

which gives us

or

  This is the food intake the animal need to consume with 30% efficiency.