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algol [13]
3 years ago
7

g power output of 87 W. At what distance will the decibel reading be 120 dB, which is noise level of a loud indoor rock concert

Physics
1 answer:
Kazeer [188]3 years ago
7 0

Given that,

Output power = 87 W

Decibel reading = 120 dB

We need to calculate the intensity of sound

Using formula of intensity of sound

dB=10\log(\dfrac{I}{I_{0}})

Put the value into the formula

120=10\log(\dfrac{I}{1\times10^{-12}})

12=log(\dfrac{I}{1\times10^{-12}})

10^{12}=\dfrac{I}{1\times10^{-12}}

I=10^{12}\times1\times10^{-12}

I=1\ W/m^2

We need to calculate the distance

Using relation of power out[ut and intensity

I=\dfrac{P}{4\pi r^2}

Put the value into the formula

1=\dfrac{87}{4\pi r^2}

r=\sqrt{\dfrac{87}{4\pi}}

r=2.63\ m

Hence, The distance is 2.63 m

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Write equations for both the electric and magnetic fields for an electromagnetic wave in the red part of the visible spectrum th
Strike441 [17]

Answer:

E=3.5(8.98*10^{6}x-2.69*10^{15}t)

B=1.17*10^{-8}(8.98*10^{6}x-2.69*10^{15}t)

Explanation:

The electric field equation of a electromagnetic wave is given by:

E=E_{max}(kx-\omega t) (1)

  • E(max) is the maximun value of E, it means the amplitude of the wave.
  • k is the wave number
  • ω is the angular frequency

We know that the wave length is λ = 700 nm and the peak electric field magnitude of 3.5 V/m, this value is correspond a E(max).

By definition:

k=\frac{2\pi}{\lambda}            

k=8.98*10^{6} [rad/m]      

And the relation between λ and f is:                

c=\lambda f

f=\frac{c}{\lambda}

f=\frac{3*10^{8}}{700*10^{-9}}

f=4.28*10^{14}

The angular frequency equation is:

\omega=2\pi f

\omega=2\pi*4.28*10^{14}

\omega=2.69*10^{15} [rad/s]

Therefore, the E equation, suing (1), will be:

E=3.5(8.98*10^{6}x-2.69*10^{15}t) (2)

For the magnetic field we have the next equation:

B=B_{max}(kx-\omega t) (3)

It is the same as E. Here we just need to find B(max).

We can use this equation:

E_{max}=cB_{max}

B_{max}=\frac{E_{max}}{c}=\frac{3.5}{3*10^{8}}

B_{max}=1.17*10^{-8}T

Putting this in (3), finally we will have:

B=1.17*10^{-8}(8.98*10^{6}x-2.69*10^{15}t) (4)

I hope it helps you!

8 0
3 years ago
A 0.90-kg falcon is diving at 28.0 m/s at a downward angle of 35° . It catches a 0.325-kg pigeon from behind in midair. What is
pashok25 [27]

Answer:

22.11 m / s

Explanation:

The falcon catches the prey from behind means both are flying in the same direction ( suppose towards the left )

initial velocity of falcon = 28 cos 35 i - 28 sin 35 j  

( falcon was flying in south east direction making 35 degree from the east )

momentum = .9 ( 28 cos 35 i - 28 sin 35 j  )

= 20.64 i - 14.45 j

initial velocity of pigeon

= 7 i

initial momentum = .325 x 7i

= 2.275 i

If final velocity of composite mass of falcon and pigeon be V

Applying law of conservation of momentum

( .9 + .325) V = 20.64 i - 14.45 j +2.275 i

V = ( 22.915 i - 14.45 j ) / 1.225

= 18.70 i - 11.8 j

magnitude of V

= √ [  (18.7 )² + ( 11.8 )²]

= 22.11 m / s

6 0
4 years ago
hey pls help with this HDJSJDH im rlly bad at this kinda stuff :,) i'll mark the correct answer brainliest
timama [110]
I am pretty sure it’s A
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DaniilM [7]

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Would appreciate Brainliest ;)

4 0
3 years ago
Atoms in a molecule are bonded together by sharing gaining or losing_
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It is by gaining! I just learned this in school. Hope this helps:)

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3 years ago
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