Two locomotive train units of equal layout lengths pass a single track sign pole in 10 seconds and 15 seconds. If each train length tracks at 120 meters, find the time parameter to pass each other completely when running in opposite directions. MCQ with Answer and Explanation
Two locomotive train units of equal layout lengths pass a single track sign pole in 10 seconds and 15 seconds. If each train length tracks at 120 meters, find the time parameter to pass each other completely when running in opposite directions.
A. 14 seconds
B. 16 seconds
C. 12 seconds
D. 10 seconds
Answer: Option C
Solution (By JKSSB Mock Tests)
Speed of first train = 120 / 10 = 12 m/s. Speed of second train = 120 / 15 = 8 m/s. Total tracking distance = 120 + 120 = 240 meters. Relative speed in opposite directions = 12 + 8 = 20 m/s. Time required = 240 / 20 = 12 seconds.
A cyclist tracks a sector distance of 24 km at a certain speed. If he drops his pace by 2 km/h, he takes 1 hour more to cover the route. Find his baseline speed.
Explanation:
Let original speed be s. 24 / (s - 2) - 24 / s = 1 => 24(2) = s(s - 2) => 48 = s(s - 2). Solving s^2 - 2s - 48 = 0 yields (s - 8)(s + 6) = 0. Since speed must be positive, s = 8 km/h.
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