The energy flux associated with solar radiation incident on the outer surface of the earth’s atmosphere has been accurately measured and is known to be 1368 W/m2. The diameter of the sun and earth are 1.39 X 109 and 1.27 X 107 m, respectively, and the distance between the sun and the earth is 1.5 X 1011 m.(a) What is the emissive radiation flux of the sun surface?(b) Approximating the sun’s surface as a black body ( = 1), what is its temperature?(c) At what wavelength is the spectral emissive power of the sun a maximum?(d) Assuming the earth’s surface to be a black body ( = 1) and the sun to be the only source of energy for the earth, estimate the earth’s surface temperature.

An external consultant recommends that a plant installs a bank of capacitors for power factor correction. this will reduce the peak electrical demand charges by an average of 93 kw every month. the plant current pays $13 per kw in peak demand charges. the capacitor bank will include 223 kw of fixed capacitors, and 183 of variable capacitors. the fixed capacitors cost $59 per kw, and the variable capacitors will cost $65 per kw. the consultant charges 21% of the equipment costs to install the capacitors. because this project will reduce the demand for the electric utility, they are prepared to provide a one-time rebate of $42 per kw of reduced demand. what is the simple payback period for this project (in years)?