Amodel test of a tractor-trailer rig is performed in a wind tunnel. the drag force, fd, is found to depend on the frontal area, a, wind speed, v, air density, r, and air viscosity, µ. the model scale is 1: 4 (e. g., 1 m in the model is equivalent to 4 m in the prototype), frontal area of the model is a = 0.625 m2 . a. obtain a set of dimensionless parameters suitable to characterize the model test results

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)?