As a car approaches a pedestrian crossing the
road, the driver blows the horn. compared to
the sound wave emitted by the horn, the sound
wave detected by the pedestrian has a
(1) higher frequency and a lower pitch
(2) higher frequency and a higher pitch
(3) lower frequency and a higher pitch
(4) lower frequency and a lower pitch

The correct answer is " higher frequency and a higher pitch".

Explanation:

Doppler effect: It is the phenomenon in which there is relative motion between the source and the listener. There is an change in the frequency.

There is increase in the frequency of the wave when the listener and the source are moving towards each other.

There is decrease in the frequency of the wave when the listener and the source are moving away from each other then the frequency decreases.

In the given problem, a car is approaching a pedestrian who is crossing the road. The driver blows the horn. The pitch depends on the frequency. Here, the source and listener are moving towards each other. The frequency of the wave increases and it will have a higher pitch.

Therefore, the correct option is (2).

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s

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