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LekaFEV [45]
2 years ago
11

An ambulance with a siren emitting a whine at 1800 hz overtakes and passes a cyclist pedaling a bike at 2.23 m/s. after being pa

ssed, the cyclist hears a frequency of 1790 hz. how fast is the ambulance moving? (take the speed of sound in air to be 343 m/s.
Physics
1 answer:
Anna71 [15]2 years ago
5 0
It's the Doppler Effect that "up and down sound." 

I was on Yahoo--- Brainly doesn't have an option for Credientials or Site credit, so I'll just put this in the quotes:


<span>The formula for doppler effect is always (s is speed and f is frequency): </span>
<span>f_perceived.by.observer = f_of.emitted.wave * (s_wave + s_observer) / (s_wave + s_source.of.wave) </span>

<span>And you should pay attention to the signs: </span>
<span>s_observer is positive if the receiver is moving towards the source, negative otherwise </span>
<span>s_source.of.wave is positive if the source is moving away from the observer, negative otherwise </span>

<span>Applying it to this case: </span>

<span>s_source.of.wave = ? (positive), speed of ambulance </span>
<span>s_observer = + 2.44 m/s speed cyclist </span>
<span>f_of.emitted.wave =1800 Hz frequency of whine </span>
<span>f_perceived.by.observer = 1760 frequency heard by cyclist </span>
<span>s_wave = 343 m/s speed of sound in air </span>

<span>Now you know every value in the equation for doppler effect except by s_source.of.wave, so you can solve for s_source.of.wave.</span>
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Answer:

a)n= 3.125 x 10^{19 electrons.

b)J= 1.515 x 10^{6 A/m²

c)V_{d =1.114 x 10^{4m/s

d) see explanation

Explanation:

Current 'I' = 5A =>5C/s

diameter 'd'= 2.05 x 10^{-3 m

radius 'r' = d/2 => 1.025 x 10^{-3 m

no. of electrons 'n'= 8.5 x 10^{28}

a) the amount of electrons pass through the light bulb each second can be determined by:

I= Q/t

Q= I x t => 5 x 1

Q= 5C

As we know that: Q= ne

where e is the charge of electron i.e 1.6 x 10^{-19C

n= Q/e => 5/ 1.6 x 10^{-19

n= 3.125 x 10^{19 electrons.

b)  the current density 'J' in the wire is given by

J= I/A => I/πr²

J= 5 / (3.14 x (1.025x 10^{-3)²)

J= 1.515 x 10^{6 A/m²

c) The typical speed'V_{d' of an electron is given by:

V_{d = \frac{J}{n|q|}

    =1.515 x 10^{6 / 8.5 x 10^{28} x |-1.6 x 10^{-19|

V_{d =1.114 x 10^{4m/s

d) According to these equations,

J= I/A

V_{d = \frac{J}{n|q|} =\frac{I}{nA|q|}

If you were to use wire of twice the diameter, the current density and drift speed will change

Increase in the diameter increase the cross sectional area and decreases the current density as it has inverse relation.

Also drift velocity will decrease as it is inversely proportional to the area

 

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PLEASE HELP! I don't get it at all! Speed is one thing; distance is another. Where is the arrow you shoot up at 50m/s when it ru
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Two airplanes leave an airport at the same time. The velocity of the first airplane is 730 m/h at a heading of 44.3 ◦ . The velo
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Answer:

So airplane will be 1324.9453 m apart after 2.9 hour

Explanation:

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Distance traveled by first plane = 730×2.9 = 2117 m

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We represent these distances as two sides of the triangle, and the distance between the planes as the side opposing the angle 38.7.

Using the law of cosine, d^2 representing the distance between the planes, we see that:

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n a downhill ski race, surprisingly, little advantage is gained by getting a running start. (This is because the initial kinetic
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Answer:

Explanation:

a ) starting from rest , so u = o and initial kinetic energy = 0 .

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= 343 m

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b )

In this case initial kinetic energy = 1/2 m v²

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= 346.125 m

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