Question

A physics student sits by the open window on a train moving at 20 m/sec towards the east. Her boyfriend is standing on the station platform, sadly watching her leave. When the train is 138 meters form the station, it emits a whistle at a frequency of 2 × 10³ Hz.

1)

What frequency does the boyfriend hear ?
f =

2)

What frequency does the physics student hear?

f =

3)

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 20 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?

f =

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

f =

Answer 1