A sound wave travels at a speed of 340 m/s. How long does it take to span a line distance of 5.1 km? MCQ with Answer and Explanation

Explanation:
Total distance = 3 * 5 = 15 km. Total time taken = 5/10 + 5/20 + 5/30 = 1/2 + 1/4 + 1/6 = (6 + 3 + 2) / 12 = 11/12 hours. Average speed = 15 / (11/12) = 180 / 11 = 16.36 km/h.

Explanation:
Speed of train = 90 * (5/18) = 25 m/s. Total distance covered in 20 seconds = 25 * 20 = 500 meters. Length of tunnel = 500 - 150 = 350 meters.

Explanation:
Time allocated to clear the platform alone = 25 - 15 = 10 seconds. Speed of train = 250 / 10 = 25 m/s. Length of train = Speed * Time to pass mast = 25 * 15 = 375 meters.