A dog barks in a park and hear 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 isA) 86.5 mB) 80.6 mC) 75 mD) 8.65 m

Let the distance between the dog and the building be x.
When the dog barks, the sound covers the distance x and gets reflected back from the building after covering distance x once again so that echo is heard.
So, the sound covers 2x distance in 0.5 s.
Distance=time×velocity2x=0.5×346x=0.5×3462=86.5 m
Therefore, the correct option is A.

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time=0.5 seconds


distance= speed x time = 346 x 0.5 = 173m

this answer should be divided by 2 because it is an echo and is reflected = 173/2 = 86.5m

A is the correct option.

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