A dog barks in a park and hears its echo after 0.5 seconds. The sound of its bark got reflected by a nearby building. The sound of speed in air is 346 m/s. The distance between the dog and the building is
A) 86.5 m
B) 80.6 m
C) 75 m
D) 8.65 m
Correct Answer:
A
Solution :
The echo is heard when the sound wave travels a distance \[2x\]. As \[\text{distance = speed }\times \text{ time}\] \[\therefore 2x=346\times 0.5\] Or \[x=\frac{346\times 0.5}{2}=86.5m\]