Posted by **Valerie** on Wednesday, April 24, 2013 at 3:32pm.

Two trains with 112-Hz horns approach one another. The slower of the two trains has a speed of 26 m/s. What is the speed of the faster train if an observer standing near the tracks between the trains hears a beat frequency of 4.7 Hz? (Express your answer to the nearest 0.1 m/s.) I tried using the equation fo = fs((1+vo/c)/(1-vs/c)) but I think I may be plugging in the values wrong. Can anyone help me?