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Lina20 [59]
3 years ago
7

A police siren sounds different as it comes close to you than when it moves away from you. what term explains how this happens?

Physics
2 answers:
andreev551 [17]3 years ago
4 0

Answer: b. the Doppler effect

Explanation:

Doppler effect describes the apparent change in the frequency heard by the listener than the frequency emitted by the source when there is relative motion between the two. When the source and listener approach each other, the apparent frequency is higher than the source and when they move away, the apparent frequency heard by the listener is lower than the source.

Due to Doppler's effect, a police siren sounds different when it comes closer than when it moves away. When it is closer, higher pitch can be heard than when it is moving past away.

Sholpan [36]3 years ago
3 0
The answer is: b. the doppler effect
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The motors that drive airplane propellers are, in some cases, tuned by using beats. The whirring motor produces a sound wave hav
sweet-ann [11.9K]

Answer:

A) 2 possible frequencies of second propellar = 424 rpm or 724 rpm

B) Correct frequency is f2 = 724 rpm

C) Reason is stated in explanation

Explanation:

A) We are given;

Frequency of first propeller; f1 = 574 rpm

Beat frequency; f_beat = 2.5 Hz = 2.5 × 60 rpm = 150 rpm

Now, formula for the beat frequency is;

f_beat = |f1 - f2|

Now, |f1 - f2| means it is inside an absolute value.

Thus, it means,

f1 - f2 = 150 or f2 - f1 = 150

Thus;

574 - f2 = 150

Or f2 - 574 = 150

So,f2 = 574 - 150 = 424 rpm or f2 = 574 + 150 = 724 rpm

2 possible frequencies of second propellar = 424 rpm or 724 rpm

B) Now, if we increase the speed of the second propellar slightly, it means that f2 will increase as well.

Now, from the 2 possible values of f2 gotten, we can see that for f1 - f2 = 150, when we increase f2, the beat frequency will reduce while for f2 - f1 = 150, when we increase f2, the beat frequency will increase.

Thus, it's the frequency of f2 gotten in f2 - f1 = 150 that is the correct answer.

Thus, when we increase the speed of the second propellar slightly, it means that;

f2 = 724 rpm

C) Answer in part B is correct because as we increase the speed of the second propellar, the frequency will also increase and the value of f2 that corresponds with an increase in speed is 724 rpm.

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Answer:

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3 years ago
A bowling ball rolls off the edge of a cliff, moving horizontally at 20 m/s. I have to plot the position of the bowling ball on
liubo4ka [24]
For counting x you use simple equation for the distance covered by the object when it moves with constant velocity:
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Add minus signs before y positions to receive graph presenting the movement of the ball.
So the points are: P1=[20,-5], P2=[40,-20], P3=[60,-45] and so on... Pn=[x,y].
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What is the kinetic energy of a ball with a mass of 0.06kg moving at 50m/s?
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Why is the power of concave lense negative​
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Answer:

because the focal length is negative.

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