A power source designed for a spot-welding process has current as a function of time given by I = 100,000t, where I is in amp and t in second. The sheet metal being spot welded is low carbon steel whose unit melting energy is 10 J/mm3. The resistance of the process is 85 micro-ohms, nugget formed is disk shape of diameter = 4 mm and thickness = 2 mm. 25% of the energy generated from the source is used to form the nugget. The time for which the current must be applied to perform the spot-welding operation is _____ seconds. (Correct upto two decimals)
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