Doppler Shift/ Doppler effect!! HELP 1. A police car is traveling at a constant speed of 110. km/h with a radar gun which generates and detects radiowaves. The police car and the ambulance drive directly towards each other. The radar gun produces radiowaves with a wavelength of 0.0440 m. An ambulance is traveling at 64.0 km/h towards an intersection The ambulance has a siren which produces sound at a frequency of 4.30 kHz. Assume the speed of sound in air is 340. m/s. (i) What is the relative speed between the police car and the ambulance? (ii) What doppler shift (Δf = f′–f) is detected by the radar gun after the radiowave has been reflected by the ambulance? 2. Relevant equations relative speed = v1 + v2 f obs = fs ((vw + v obs) / (vw + vs)) Vw = 340 m/s (speed of sound...) v obs = 64km/h (17.778 m/s) vs = 110 km/h (30.556 m/s) fs = 4.3 kHz (Δf = f′–f) f = 4.3 kHz v = fλ (I got λ = 0. 044 so what am I using it for??) 3. The attempt at a solution A) Easy 110 +64 = 174 km/h B) The problem child. I plug in with the equation above, with + because the ambulance and the police are moving towards each other, but I don't get the right answer (2,200 Hz) I know I need to find Δf, but how do I go about to find it? Why is this equation not working, and which equation am I meant to use? Whats the radar wavelength for? How do I implement it? Any help would be much appreciated!!