posted by storm .
A hiker determines the length of a lake by listening for the echo of her shout reflected by a cliff at the far end of the lake. She hears the echo 1.7 s after shouting. Estimate the length of the lake.
For the person to hear the echo, the sound must travel through the length of the lake and return, make two trips through the length of the lake.
Speed of sound = 340 m/s
Distance travelled in 1.7 s = 340*1.7 m
Length of lake
= distance travelled / 2