Question

.. + -/1 points SerCP10 14.P.025.WI. Two trains on separate tracks move toward each other. Train 1 has a speed of 117 km/h; train 2, a speed of 73.0 km/h. Train 2 blows its horn, emitting a frequency of 500 Hz. What is the frequency heard by the engineer on train 1?

Answer 1

The speed of the train 1, v₀=117 km/h= 32.5 m/s

The speed of the train 2, v_s= 73km/h= 20.28 m/s

Speed of sound in air, v= 343m/s

Train 2 blowing horn of frequency, f= 500 Hz

Now, as train 1 and 2 are moving towards each other, the Dopler effect formula gives the apparent frequency heard by the engineer on train 1 is,

$f'=(\frac{v+v_0}{v-v_s})f=\frac{343+32.5}{343-20.28}*500=581.77 Hz$