(uscs units) an ecm operation is used to cut a rectangular-shaped blind hole into a block of copper (valence = 1). the frontal working area of the electrode is 0.750 in by 2.50 in. applied current = 900 a and voltage = 15 volts. (a) if the process is 94% efficient, determine the rate of metal removal. (b) if the electrolyte resistivity = 7.5 ohm-in, determine the working gap. (c) if the gap created at the sides of the rectangular-shaped electrode is equal to the working gap from part (b), determine the area of the rectangular-shaped hole that is created (ignore rounding at corners). (d) how much time is required to cut the blind hole to a depth of 1.00 in.