Solar radiation is incident on the outer surface of a spaceship at a rate of 420 btu/h·ft2. the surface has an absorptivity of αs = 0.10 for solar radiation and an emissivity of ε = 0.6 at room temperature. the outer surface radiates heat into space at 0 r. if there is no net heat transfer into the spaceship, determine the equilibrium temperature of the surface.

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)?