While talking to a friend, a construction worker momentarily set her cell phone down on one end of an iron rail of length 7.50 m. At that moment, a second worker dropped a wrench so that it hit the other end of the rail. The person on the phone detected two pulses of sound, one that traveled through the air and a longitudinal wave that traveled through the rail. (Assume the speed of sound in iron is 5,950 m/s and the speed of sound in air is 343 m/s).
A) Which pulse reaches the cell phone first?
B) Find the separation in time (in s) between the arrivals of the two pulses.