[administration]

Q. A locomotive requires an energy of E units per second, when it travels at a speed of s m/sec. If E = s3 – 20s2 + 124s, find the maximum possible distance that the locomotive can travel, given that it has a total energy supply of 72 × 105 units.

216 km

256 km

300 km

360 km

 

asked by Rajat Gupta

[administration]

We need to minimize E/s

E/s = s^2 – 20s + 124 = (s – 10)^2 + 24
So, s = 10

=> E/s = 24

=> d = 72*10^5/24 = 300 km

 

soln by Hemant Yadav

[Author]

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