In an arc welding operation, carried out with apower source maintained at 40 volts and 400amperes,..

In an arc welding operation, carried out with apower source maintained at 40 volts and 400amperes, the consumable electrode melts and justfills the gap between the metal plates to be buttwelded.The heat transfer efficiency for the processis 0.8, melting efficiency is 0.3 and the heat requiredtomelt the electrode is 20 J/mm3. If the travel speedof the electrode is 4 mm/s, the cross-sectional area,inmm2, of the weld joint is _______