We often speak of the "root mean square" or rms displacement of a diffusing object in order to quantify the average distance a diffusing particle moves in a given amount of time. This rms displacement is simply given by the square root of the average of the square of the displacement. Considering again how the average of the square of the displacement varies with time in the diffusion displacement equation, if a particle, on average, diffuses 1.0 mm in one hour, how long (in hours) will it take for the particle to diffuse 9 mm (on average)

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)?