A composite plane wall consists of a Li = 50 mm thick layer of insulation (ki = 0.05 W/m·K) and a Ls = 25 mm thick layer of siding (ks = 0.10 W/m·K). The inner temperature of the insulation is 25oC. The outer temperature of the siding is -10oC. Steady state conditions apply. Determine the temperature at the interface between the two layers, in oC, and the rate of heat transfer through the wall, in W per m2 of surface area.

Identify the theory that can be used to explain each phenomenon. answers diffraction: wave theory interference: wave theory reflection: both particle and wave theories refraction: both particle and wave theories

Astone is dropped from the upper observation deck of a tower, 250 m above the ground. (assume g = 9.8 m/s2.) (a) find the distance (in meters) of the stone above ground level at time t. h(t) = (b) how long does it take the stone to reach the ground? (round your answer to two decimal places.) s (c) with what velocity does it strike the ground? (round your answer to one decimal place.) m/s (d) if the stone is thrown downward with a speed of 2 m/s, how long does it take to reach the ground? (round your answer to two decimal places.) s

Determine the force the sun exerts on an object with a mass of 80.0 kg if that object is on the earth. what is the force exerted by the moon on the same object? what is the force the earth exerts on it?