The police car with its 300-hz siren is moving away from the warehouse at a speed of 16.0 m/s . . what frequency does the driver of the police car hear reflected from the warehouse? . use 344m/s for the speed of sound in air.

= 286.05 Hz

We can use or employ the Doppler equation:

fl = fs[(c±vl)/(c-/+vs)

where,

The source will be the origin of the reflected signal (i.e.the

warehouse). So that, velocity of source: vs = 0

The listener is the policeman moving away from the source

with velocity: vl = 16 m/s

Therefore, the Doppler equation. becomes:  

fl = fs [(c – vl)/c]

= 300[(344-16)/344]

= 286.04 Hz

where, fl is the frequency of the reflected sound heard by

the police officer.

the higher the current the higher the mag field around it the higher the influence on the compass

force tends to be low and long diustance masses are high