# Physics

posted by
**James**
.

1. A train whistle has a frequency of 1000 Hz. If the train is speeding

at a velocity of 60 km/h past a stationary railroad crossing

attendant, what is the apparent frequency a) as the train approaches him, b) as it moves away from him?

Assume speed of sound to be 350 m/s.

2. A second train is approaching the first train (above) with a speed of

60 km/h. Obtain the frequency of the whistle of the first as heard by

the engineer of the second train.

3. Sound is reflected by a screen moving with a speed 20 km/h toward

the source and observer. If the frequency of the source is 450 khz,

what is the apparent frequency of the reflected sound?

Help me solve these questions