Author Question: When you hear the horn of a car that is approaching you, the frequency that you hear is larger than ... (Read 78 times)

joe · **on:** Jul 28, 2018

When you hear the horn of a car that is approaching you, the frequency that you hear is larger than that heard by a person in the car because for the sound you hear
a. wave crests are farther apart by the distance the car travels in one period. b. wave crests are closer together by the distance the car travels in one period. c. the car gets ahead of each wave crest before it emits the next one. d. the speed of sound in air is increased by the speed of the car.
e. a speeding car emits more wavecrests in each period.

Question 2

A truck moving at 36 m/s passes a police car moving at 45 m/s in the opposite direction. If the frequency of the siren is 500 Hz relative to the police car, what is the change in frequency (in Hz) heard by an observer in the truck as the two vehicles pass each other? (The speed of sound in air is 343 m/s.)
a. 242
b. 238
c. 240
d. 236
e. 234