A) \[1.2\times {{10}^{5}}kcal\]
B) \[2.4\times {{10}^{5}}kcal\]
C) \[4.8\times {{10}^{5}}kcal\]
D) \[6\times {{10}^{5}}kcal\]
Correct Answer: B
Solution :
Heat produced is equal to the kinetic energy of train \[Q=\frac{1}{4.2}\left( \frac{1}{2}m{{\upsilon }^{2}} \right)\] \[\{72km/hr72\times 1000/3600=20m/s\}\] \[=\frac{1}{4.2}\times \frac{1}{2}\times 5\times {{10}^{6}}\times 20\times 20=2.4\times {{10}^{5}}kcal\]
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