2019 · Q45
An echo is heard after 5 seconds of the production of sound which moves with a speed of 340 m/s. What is the distance of the mountain from the source of sound which produced the echo ?
General KnowledgePhysics
- A0.085 km
- B0.85 km
- C0.17 km
- D1.7 km
Explanation
The echo returns after the sound travels to the cliff and back: 2d = v × t = 340 × 5 = 1700 m, so the one-way distance d = 850 m = 0.85 km. Forgetting to halve the round trip gives the wrong options 1.70 km or 3.40 km. Hence 0.85 km.