A6-in. insulated frame wall of a house has an average thermal conductivity of 0.04 btu/h·ft·°r. the inner surface of the wall is at 68°f, and the outer surface is at 40°f. the temperature varies linearly through the wall. determine at steady state the rate of heat transfer through the wall, in btu/h. if the wall is 20 ft × 10 ft, determine the total amount of energy transfer in 10 hours, in btu.

You are the coordinator for a program that is going to take place at night in a rectangular amphitheater in the mountains. you will have no access to any electricity, but you must be able to illuminate the entire grounds. you know the intensity of the light from a lantern varies inversely as the square of the distance from the lantern. suppose the intensity is 90 when the distance is 5 m. a. write an equation to model the situation. b. solve for the constant of variation. c. write the equation to model the situation using the constant () of variation. d. you have been given lanterns with 40 light intensity. use your equation to solve for the distance from the lantern. e. you need to illuminate 225 km. how many meters do you need to light? f. how many lanterns will you need?