Answer:
f' =1064.1025 Hz
Explanation:
We know that from doppler's effect
[tex]f'=\frac{v+v_0}{v-v_s}f[/tex]
f'= observed frequency
f= actual frequency =1000 Hz
v= velocity of sound waves = 332 m/s
v_o= velocity of observer =0
v_s= velocity of source. ( let velocity of car be 20 m/s)
therefore,
[tex]f'=\frac{332+0}{332-20}\times1000[/tex]
f' =1064.1025 Hz
