A train $200$ m long is running at $72$ km/h. The time it takes to cross a stationary pole is:

A train $200$ m long is running at $72$ km/h. The time it takes to cross a stationary pole is:
  1. $8$ s
  2. $10$ s
  3. $12$ s
  4. $15$ s

Solution

$72$ km/h $= 72 \times \dfrac{5}{18} = 20$ m/s. Time $= \dfrac{200}{20} = 10$ s.

Asked in: IMO

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