The echo of a gun shot is heard $8\, sec$. after the gun is fired. How far from him is the surface that reflects the sound .... $m$ (velocity of sound in air $= 350 \,m/s$)
A$1400$
B$2800$
C$700 $
D$350 $
Medium
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A$1400$
a (a) Suppose the distance between shooter and reflecting surface is $d$.
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