GATE 2021 MT – Question 50
A 3000 W machine makes a continuous fillet weld at 6 mm/s. Heat-transfer factor is 0.6, melting factor 0.5, and unit energy for melting 6 J/mm$^3$. The weld cross-sectional area is ______ mm$^2$ (nearest integer).
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Show answer and explanation
Correct answer: 25 to 25
Explanation
Power used for melting is 3000×0.6×0.5=900 J/s. Volume melted per second is Av=6A mm³/s and requires 6 J/mm³, so 900=36A.
Therefore **A=25 mm²**.