Q. A stationary railroad whistle is sounded. An echo is heard 5.0 seconds later by the train's engineer. If the speed of sound is 343 m/s, how far away is the reflecting surface?
Q. An unstretched spring has a length of 0.30 m. When the spring is stretched to a total length of 0.60 m, it supports traveling waves moving at 4.5 m/s. How fast will waves travel on this spring if it is stretched to 0.90 m?