Multiple choice

A train, 100 m long, moving at a speed of 50 km/hr crosses another train, 120 m long, coming from the opposite direction in 6 seconds. The speed of the second train is

  1. 132 km/hr

  2. 82 km/hr

  3. 60 km/hr

  4. 50 km/hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Relative speed = (100 + 120)m / 6s = 220/6 m/s = 110/3 m/s. Convert to km/hr: (110/3) * (18/5) = 132 km/hr. Since they are moving in opposite directions, relative speed = v1 + v2. 50 + v2 = 132 => v2 = 82.

AI explanation

Using the relative speed formula for objects moving in opposite directions, the total distance of 100 m + 120 m equals the relative speed multiplied by 6 seconds. This gives a relative speed of 220 m / 6 s, which simplifies to 110/3 m/s. Converting this relative speed back to km/hr requires multiplying by 18/5, resulting in 660 km/hr. Since the first train travels at 50 km/hr, the speed of the second train is 660 - 50, giving 82 km/hr.

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