Doppler Effect- Observer On Angle To Source Plz help- I've been working on this for 2 days and I'm down to my last teaspoon of coffee powder. Even having the answer didn't help! I think sleepness is turning me into a zombie ...prehaps eating brains will help me solve this problem... An ambulance is traveling at 84.0 km/h towards an intersection. Jim stops his car to give way to the ambulance as shown in the diagram. θ = 42.0 °. http://oasis.phy.auckland.ac.nz/oasis/a/att/qtatt/888/2/52/amburightjimrest.gif The ambulance has a siren which produces sound at a frequency of 2.8 kHz. Assume the speed of sound in air is 340.0 m/s. What is the doppler shift (Δf = f′–f) heard in the siren sound by Jim, when Jim and the ambulance are positioned as shown on the diagram above? Ans: 0.148 kHz 3. The attempt at a solution I figured f' =f [ v/(v-v(source) ] then Δf = f′–f but no luck there Does it have something to do with the angle?