Question

A sound wave travels at 345 m/s in air and 5.9 km/s in steel. A train sounds off its whistle twice: Once at 8:55am and another at 9:00am just before leaving the station. A group of train robbers about 7.4 km away heard the first whistle sound in the air and put their ears to the rails to hear the second whistle. A) What is the time difference between hearing the whistle from the rails and hearing it from the air? B) The train sounds off its whistle again somewhere along the way. The interval between the two sounds has decreased by a factor of 2. Where is the train now?

Answer 1