A person watches an ambulance drive by them while emitting a steady sound from its siren. When the ambulance passes the person (switching from moving towards him to moving away from him), the perceived frequency of the sound he receives decreases by 13.5 percent. How fast is the ambulance driving? Give your answer as a positive number. Assume room temperature air.

the five characteristics of adolescence are biological growth and development, and undefined status, increased decision making, increased pressure and the search of self.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

answerdmitry mendeleyev made a workable classification of the elements