A physics student sits by the open window on a train moving at 25 m/sec towards

Question

A physics student sits by the open window on a train moving at 25 m/sec towards the east. Her boyfriend is standing on the station platform, sadly watching her leave. When the train is 10 meters from the station, it emits a whistle at a frequency of 3 × 103 Hz.

What frequency does the physics student hear?

A chemistry student (with nothing better to do than ride around on trains all day) is on a west bound train moving at a velocity of 15 m/sec towards the station. Before the two trains pass each other, what frequency will he hear from the train whistle from the physics student's train?

What frequency will the chemistry student hear after his train passes the physics student's train?

Now, a wind is blowing to the east at 10 m/sec. What frequency would the boyfriend hear in this case?

What frequency would the physics student hear?

Explanation / Answer

Physics student hears a frequency of same as that of whisted

this is = 3 e 3 Hz

-----------------------------------

from Doppler effect

frequency iwhen objects approaching each other is

fs = f *(V +V0)/(V-Vs)

fs = 3e3 * ( 340 + 15)/(340-25)

fs = 3.38 e 3 Hz

-----------------------------------------------------
frequency when objects move away each other is

fs = f *(V -V0)/(V+Vs)

fs = 3e3 * ( 340 -15)/(340 +25)

fs = 2.671 e 3 Hz

----------------------------------------------
When only source moves away from observer

so

f = 3 e3 * V/(V+vs)

f = 3e 3 * 340/ (340+ 10)

f = 2.914 e 3 Hz

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.