An explosion takes place at a certain distance from an army camp. As soon as the sensor in the camp — CSAT 2026 Answer & Explanation

2026

An explosion takes place at a certain distance from an army camp. As soon as the sensor in the camp receives the sound of the explosion, a drone starts flying towards the spot of explosion. The drone clicks a picture from the spot and the camp receives it at the same time. Immediately another drone starts flying to the spot and it also sends a picture as soon as it reaches the spot. The two pictures were received at 5:02 PM and 5:05 PM, respectively. If the speed of the drones is 30 m/s, at what time did the explosion take place? Assume that the speed of sound is 300 m/s.

Explanation

Let $d$ be the distance from the camp to the explosion; the time taken for sound to reach the camp is $\frac{d}{300}$ seconds. The first drone takes $\frac{d}{30}$ seconds to reach the explosion and send the picture back, while the second drone takes 3 minutes longer, leading to the equation:

\frac{d}{30} + 3 \times 60 = \frac{d}{300} + \frac{d}{30}

Solving yields $d = 8400$ meters, and calculating the time of the explosion to receive the first picture at 5:02 PM gives $4:58:42 PM$ .

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