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Paraphin [41]
2 years ago
9

The low-frequency speaker of a stereo set produces 10.0 W of acoustical power. If the speaker projects sound uniformly in all di

rections, at what distance from the speaker is the intensity level 80.0 dB
Physics
1 answer:
Paha777 [63]2 years ago
6 0

Answer:

the required distance is 89.125 m

Explanation:

Given the data in the question;

we know that, sound intensity B in decibels of sound is;

β(dB) = 10log₁₀( I / I_0 )

where intensity I = power / area carried by wave

I_0 = 10⁻¹² W/m² { minimum threshold intensity }

Now,

intensity I = power / area carried by wave = P/A = P/4πr² { spherical  }

given that; β = 80.0 dB and P = 10 W

so

β(dB) = 10log₁₀( I / I_0 )

we substitute

80 = 10log₁₀( P / 4πr²× I_0)

80 = 10log₁₀( 10 / 4πr²× 10⁻¹² )

8 = log₁₀(10) - log₁₀( 4πr²× 10⁻¹² )  

8 = 1 - log₁₀( 4πr²× 10⁻¹² )

8 - 1 = -log₁₀( 4πr²× 10⁻¹² )

7 = -log₁₀( 1.2566 × 10⁻¹¹ × r² )

7 = -[ log₁₀( 1.25 × 10⁻¹¹) + log₁₀( r² ) ]

7 = -[ -10.9 + log₁₀( r² ) ]

7 = 10.9 - log₁₀( r² )

-log₁₀( r² ) = 7 - 10.9

-log₁₀( r² )  = - 3.9

log₁₀( r² ) = 3.9

2log₁₀r = 3.9

log₁₀r  = 3.9 /2

log₁₀r = 1.95

r = 89.125 m

Therefore, the required distance is 89.125 m

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8_murik_8 [283]

Answer:

Explanation:

There will be loss of potential energy due to loss of height and gain of kinetic energy .

loss of height = R - R cos 14 ,    R is radius of hemisphere .

R ( 1 - cos 12 )

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h = .286 m

loss of potential energy

= mgh

= m x 9.8 x .286

= 2.8 m

gain of kinetic energy

1/2 m v ² = mgh

v² = 2 g h

v²  = 2 x 9.8 x 2.8

v = 7.40 m /s

4 0
3 years ago
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Two wheel gears are connected by a chain. The larger gear has a radius of 8 centimeters and the smaller gear has a radius of 3 c
dezoksy [38]

Answer:

B.The linear velocity of the gears is the same. The linear velocity is 432π centimeters per minute.

Explanation:

As we know that the small gear completes 24 revolutions in 20 seconds

so the angular speed of the smaller gear is given as

\omega = 2\pi\frac{24}{20}

\omega = 2.4\pi rad/s

Now we know that the tangential speed of the chain is given as

v = r \omega

so we have

v = (3 cm)(2.4\pi)

v = 7.2 \pi cm/s

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Since both gears are connected by same chain so both have same linear speed and hence correct answer will be

B.The linear velocity of the gears is the same. The linear velocity is 432π centimeters per minute.

8 0
3 years ago
In tae-kwon-do, a hand is slammed down onto a target at a speed of 10 m/s and comes to a stop during the 7.0 ms collision. Assum
wlad13 [49]

Answer:

(A) Impulse = 9Ns

(B) F = 1286N

Explanation:

Impulse = change in momentum = m(v-u)

v = 0 (the hand comes to a stop)

u = -10m/s

Mass = 0.9kg

Impulse = 0.9 ×(0- (-10))

= 9Ns

(B) F×t = Impulse

F = Impulse/ t

t = 7ms = 7×10-³

F = 9/ (7×10-³)

F = 1286N.

5 0
3 years ago
If a 0.200-kilogram ball sits on a shelf 2.00 meters from the floor, how much mechanical energy (me) does it possess? More than
iogann1982 [59]

Answer:

Mechanical energy  = 3.92 J

exactly 3.92 j

Explanation:

As we know that mechanical energy is sum of kinetic energy and potential energy of the system

so here we can say that mechanical energy is sum of kinetic energy of ball and its potential energy

Since ball is at rest so kinetic energy of the ball must be ZERO

Now for potential energy we know that

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now we know

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now for potential ene'rgy

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U = 3.92 J

so mechanical energy is given as

Mechanical Energy = 3.92 + 0 = 3.92 J

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What are the three symbols used in Ohm's law. Explain what each symbol represents and give the units for each of the variables.
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Answer:

Step by step explanation:

6 0
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