a man standing on railway platform listening to the whistle of an engine tat passes the man at constant speed at time \" t'' \".Hoow does the frequency as heard by man changes wid time.Sketch the graph of \"f vs t\".

frequency heard by listener from t=0 (when train was approaching and was far apart ) to t=T (when train passes the listener) is constant & given by

f = f_o(V/V-V_t)                      (V_t = speed of train, V speed of sound)

when train has passed the listener then frequency again becomes constant but now it is f¹

f¹ = f_o(V/V+V_t)

now plot this graph by using these two eq

Approved