A person rings a metallic bell near a strong concrete wall. He hears the echo after 0.3 s. If the sound moves with a speed of 340 m/s, how far is the wall from him?
[CDS I 2016]
1) 102 m
2) 11 m
3) 51 m
4) 30 m
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A person rings a metallic bell near a strong concrete wall. He hears the echo after 0.3 s. If the sound moves with a speed of 340 m/s, how far is the wall from him?
[CDS I 2016]
1) 102 m
2) 11 m
3) 51 m
4) 30 m
3) 51 m
Source- 9th NCERT
d = 340 * 0.3 = 102
But.. wait
Echo means the distance of sound is twice..
Right…
Divide by 2
102/2 = 51 m