1. The problem statement, all variables and given/known data A fire truck emitting a 450 Hz signal passes by a stationary detector. The difference in frequency measured by the detector is 58 Hz. If the speed of sound is 345 m/s, how fast is the fire truck moving? 2. Relevant equations frequency of observer = (velocity of sound + velocity of detector / velocity of sound + velocity of source) f0 3. The attempt at a solution f obs (frequency of observer) = 450 Hz + 58 Hz = 508 Hz v sound (velocity of sound) = 345 m/s v detector = 0 f0 (frequency of source) = 450 Hz v source = ? How would I solve for velocity of source? I tried plugging all of the above variables into the equation and isolating the variable but I got a totally wrong answer and I'm not sure why.