Physics

Problem

A student stands midway between two parallel, large, vertical concrete walls and claps loudly. He hears the first echo after

0.20\,\text{s}

and the second echo after another

0.20\,\text{s}

. If the speed of sound is

340\,\text{m s}^{-1}

, what is the separation between the two walls? a)

102\,\text{m}

68\,\text{m}

34\,\text{m}

136\,\text{m}