A boy standing a distance from the foot of a tall cliff claps his hands and hears an echo 0.5s later. If the speed of sound is 340ms1, how far is he from the cliff?

A boy standing a distance from the foot of a tall cliff claps his hands and hears an echo 0.5s later. If the speed of sound is 340ms1, how far is he from the cliff?

A 17m
B 34m
C 85m
D 170m
E 680m

waec 1988 physics

The correct answer is C. 85m

X = vt/2 = (340 x 0.5)/2 = 85m

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