Question

LEARN MORE REMARKS If the train were going away from the observer, v, - -40.0 m/s would have been chosen Instead. QUESTION Does the Doppler shift change due to temperature variations? If so, why? For typical daily variations in temperature in a moderate climate, would any change in the Doppler shift be best characterized as nonexistent, small, or large? Yes. A change in temperature changes the speed of sound and the Doppler shift, but only Insignificantly No. Temperature does not enter into the calculation of the Doppler shift. Yes. A change in temperature changes the speed of sound and the Doppler shift, causing changes of a few percent. Yes. A change in temperature changes the speed of sound and the Doppler shift, easily doubling or tripling the size of the shift. PRACTICE IT Use the worked example above to help you solve this problem. A train at a speed of 44.6 m/s sounds it whistle, which has a frequency of 5.13 X 102 Hz. Determine the frequency heard by a stationary observer as the train approaches the observer. The ambient temperature is 21.1°C. EXERCISE HINTS: GETTING STARTED I'M STUCK! Determine the frequency heard by the stationary observer as the train recedes from the observer. frequency -

Answer 1

Question :

Yes. A change in temperature changes the speed of sound and the Doppler shift, causing changes of a few percentage.

practice it:
speed of sound, v_sound = vo + 0.6*T

= 331.5 + 21.1*0.6

= 344 m/s

v_source = 44.6 m/s
f = 5.13*10^2 Hz
f' = ?

f' = f*v_sound/(v_sound - v_source)

= 5.13*10^2*344/(344 - 44.6)

= 589 Hz

Excericise :

f' = f*v_sound/(v_sound + v_source)

= 5.13*10^2*344/(344 + 44.6)

= 454 Hz