How are radar and an approaching siren different? How are they similar? A. Radar uses sound waves, and the siren uses radio, but both exhibit
the Doppler effect
B. Radar uses radio, and the siren uses sound waves, but both exhibit
the Doppler effect
C. The Doppler effect can be observed only with radar, but both
devices use sound waves.
D. The Doppler effect can be observed only in the approaching siren,
but both devices use radio.

b

Explanation:

answer

i think the answer is a) as air pressure in an area increases, the density of the gas particles in that area decreases.

hope it

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.