The frequency F of a fire truck siren heard by a stationary observer is given below where av represents the velocity of the accelerating fire truck in meters per second see figure Round your answers to 3 decimal places 131 100 311 v a Find the rate of change of F with respect to v when the fire truck is approaching at a velocity of 27 meters per second use v b Find the rate of change of F with respect to v when the fire truck is moving away at a velocity of 27 meters per second use v