An ambulance approaches an observer at 31.5 m/s on a day when the speed of sound is 341 m/s. If the frequency heard is 525 Hz, what is the actual frequency of the siren?

d. air pressure decreases as altitude increases.

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.

no. bullets are macro objects. wave nature is for light waves, extremely tiny particles. if a light particle was the size of your finger, the bullet would be the size of the universe. so basically, that huge difference in size makes the wave nature of matter insignificant.