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3 years ago

What is the observed frequency of a siren with a frequency of

Physics

1 answer:

Yakvenalex [24]3 years ago

7 0

Answer: The observed frequency is 518.6 Hz

Explanation:

By the Doppler Effect, we know that:

f' = ((v + v0)/(v - vs))*f

where f' is the perceived frequency.

v is the velocity of the wave, in this case 330m/s

v0 is the velocity of the receptor, in this case 0m/s

vs is the velocity of the source, in this case -50m/s (the minus sign is because it is coming thowards us)

f is the original frequency, f = 440hz.

then we have:

f' = 440hz*(330m/s)/(330m/s - 50m/s) = 518.6 Hz

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Answer : The kinetic energy depends directly on the mass of a particle.

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An object covers a distance of 8 meters in the first second of travel, another 8 meters

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2 years ago

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A small electric motor produces a force of 5 N that moves a remote-control car 5 m every second. How much power does the motor p

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Explanation:

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Velocity, v = 5 m/s

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3 years ago

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An atom of carbon has a radius of 67.0 pm and the average orbital speed of the electrons in it is about 1.3 x 10⁶ m/s.

adoni [48]

Answer :

The least possible uncertainty in an electron's velocity is, $4.32\times 10^{5}m/s$

The percentage of the average speed is, 33 %

Explanation :

According to the Heisenberg's uncertainty principle,

$\Delta x\times \Delta p=\frac{h}{4\pi}$ ...........(1)

where,

$\Delta x$ = uncertainty in position

$\Delta p$ = uncertainty in momentum

h = Planck's constant

And as we know that the momentum is the product of mass and velocity of an object.

$p=m\times v$

or,

$\Delta p=m\times \Delta v$ .......(2)

Equating 1 and 2, we get:

$\Delta x\times m\times \Delta v=\frac{h}{4\pi}$

$\Delta v=\frac{h}{4\pi \Delta x\times m}$

Given:

m = mass of electron = $9.11\times 10^{-31}kg$

h = Planck's constant = $6.626\times 10^{-34}Js$

radius of atom = $67.0pm=67.0\times 10^{-12}m$ $(1pm=10^{-12}m)$

$\Delta x$ = diameter of atom = $2\times 67.0\times 10^{-12}m=134.0\times 10^{-12}m$

Now put all the given values in the above formula, we get:

$\Delta v=\frac{6.626\times 10^{-34}Js}{4\times 3.14\times (134.0\times 10^{-12}m)\times (9.11\times 10^{-31}kg)}$

$\Delta v=4.32\times 10^{5}m/s$

The minimum uncertainty in an electron's velocity is, $4.32\times 10^{5}m/s$

Now we have to calculate the percentage of the average speed.

Percentage of average speed = $\frac{\text{Uncertainty in speed}}{\text{Average speed}}\times 100$

Uncertainty in speed = $4.32\times 10^{5}m/s$

Average speed = $1.3\times 10^{6}m/s$

Percentage of average speed = $\frac{4.32\times 10^{5}m/s}{1.3\times 10^{6}m/s}\times 100$

Percentage of average speed = 33.2 % ≈ 33 %

Thus, the percentage of the average speed is, 33 %

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3 years ago