Speed in air is 340m.s Siren of ambulance emits waves of frequency 980Hz A detector at the scene measures the frequency as 1050Hz h0w d0 I w0rk this 0ut

Question

1050 = 340 / 340 - vs (980)
1050 = 1 - vs (980)
1050 = -vs (980)
1050 + vs = 980
1050/1050 + vs = 980 / 1050
vs = 980 / 1050
Vs = 0.93

Answer 1

Fd = (Vs+Vd)/(Vs-Va)*Fa = 1050 Hz.
(340+0)/(340-Va) * 980 = 1050
Divide both sides by 980:
340/(340-Va) = 1.0714
364.29-1.0714Va = 340
-1.0714Va = 340-364.29 = -24.29
Va = 22.7 m/s. = Velocity of the ambulance.

Vs = Velocity of sound.
Vd = Velocity of the detector.