GATE 2021 PI – Question 55
A sand-cast disk is 50 mm thick and 1.0 m in diameter. Chvorinov’s equation is $t=B(V/A)^2$. Thickness and diameter are both halved to 25 mm and 0.5 m under identical casting conditions. Find percentage reduction in solidification time to one decimal.
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Correct answer: 74.5 to 75.5
Explanation
All dimensions scale by 1/2, so V scales by 1/8 and A by 1/4. Thus V/A halves and solidification time becomes (1/2)² = 1/4 of original. Reduction = 100(1−1/4) = **75.0%**.