COMEDK 2023 Shift 1 Paper

To find the time taken by the drone to cross the train, we first need to determine the relative speed of the drone with respect to the train. Since the drone and the train are moving in opposite directions, their speeds will be added to find the relative speed.
The speed of the drone =10m∕ s (west)
The speed of the train =20m∕ s (east)
So, the relative speed of the drone with respect to the train is:
Relative speed = Speed of the drone + Speed of the train =10m∕ s+20m∕ s=30m∕ s
Next, to find the time taken by the drone to cross the train, we use the formula for time, which is:
‌ Time ‌=‌

‌ Distance ‌

‌ Speed ‌

In this case, the distance to be covered by the drone is equal to the length of the train, which is 270m.
Therefore, the time taken by the drone to cross the train is:
‌ Time ‌=‌

270m

30m∕ s

=9 s
Thus, the correct answer is Option D: 9 s.