A fire truck's siren at rest wails at 1450 Hz ; standing by the roadside as the truck approaches, you hear it at 1650 Hz. How fast is the truck going? (m/s)

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.

this would be about 43%