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Anon25 [30]
3 years ago
7

If two firecrackers produce a sound level of 81 dBdB when fired simultaneously at a certain place, what will be the sound level

if only one is exploded?
Physics
1 answer:
Mrac [35]3 years ago
5 0

Answer:

77.96dB

Explanation:

Recall that decibels are a unit of measuring intensity of sound, and depend on the logarithm of the intensity

the intensity, measured in decibels is given by:

I(db)=10log(I/I0)

I is the intensity in MKS units; I0 is the threshold intensity for human hearing (10^-12 W/m^2)

Thus, if the two sounds together have a dB of 81, we know:

81=10log(I/I0)

using the data above, we can find the intensity of the two sounds to be

0.000125 W/m^2

therefore, one firecracker has an intensity half of that, or 0.0000625W/m^2

now use this value to find the dB of one firecracker:

I(dB0=10log(0.0000625/10^-12)=77.96dB

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Explanation:

F=(k*q1*q2)/(r^2)

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Students in science class were asked to do an experiment with a can of soda. They placed an unopened can of soda on a digital sc
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A commuter backs her car out of her garage with an acceleration of 1.40 m/s2.A) How long does it take her to reach a speed of 2.
AURORKA [14]

Answer:

(A) 1.43secs

(B) -2.50m/s^2

Explanation:

A commuter backs her car out of her garage with an acceleration of 1.40m/s^2

(A) When the speed is 2.00m/s then, the time can be calculated as follows

t= Vf-Vo/a

The values given are a= 1.40m/s^2 , Vf= 2.00m/s, Vo= 0

= 2.00-0/1.40

= 2.00/1.40

= 1.43secs

(B) The deceleration when the time is 0.800secs can be calculated as follows

a= Vf-Vo/t

= 0-2.00/0.800

= -2.00/0.800

= -2.50m/s^2

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3 years ago
What variable can affect the amount of fruit produced by an apple tree
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Read 2 more answers
Given three vectors A = 24i + 33j, B = 55i - 12j and C = 2i + 43j (a) Find the magnitude of each vector. (b) Write an expression
slega [8]

Answer:

(a) , .  and .

(b)\vec A - \vec C=22 \hat i -10 \hat j.

(c)|\vec A - \vec B|=63.13 and the direction \theta = 124.56°.

Explanation:

Given that,

,

and

\vec {C}=2 \hat i +43 \hat j

(a) The magnitude of a vector is the square root of the sum of the square of all the components of the vector, i.e. for a ,.

So, the magnitude of the is

|\vec A|=\sqrt {24^2+ 33^2}

\Rightarrow |\vec A|=\sqrt {1665}

.

The magnitude of the is

|\vec B|=\sqrt {55^2+ (-12)^2}

\Rightarrow |\vec B|=\sqrt {3169}

.

And, the magnitude of the is

|\vec C|=\sqrt {2^2+ 43^2}

\Rightarrow |\vec C|=\sqrt {1853}

.

(b) The difference between the two vectors is the difference between the corresponding components of the vectors. So, the required expression of is

\vec A - \vec C=(24 \hat i +33 \hat j) - (2 \hat i +43 \hat j)

\Rightarrow \vec A - \vec C=24 \hat i +33 \hat j - 2 \hat i -43 \hat j

\Rightarrow \vec A - \vec C=22 \hat i -10 \hat j

(c) The expression of is

\vec A - \vec N=(24 \hat i +33 \hat j) - (55 \hat i -12 \hat j)

\Rightarrow \vec A - \vec B=24 \hat i +33 \hat j - 55\hat i +12 \hat j

\Rightarrow \vec A - \vec B=-31 \hat i +45 \hat j\;\cdots (i)

The magnitude of is

|\vec A - \vec B|=\sqrt {(-31)^2+55^2}

\Rightarrow |\vec A - \vec B|=\sqrt {3986}

\Rightarrow |\vec A - \vec B|=63.13

Now, if a vector \vec V= -\alpha \hat i +\beta \hat j in 3rd quadrant having direction \theta with respect to \hat i direction, than

in the anti-clockwise direction.

Here, from equation (i), for the vector \vec A - \vec C, \alpha=31 and \beta=45.

\Rightarrow \theta = \pi-\tan ^{-1}\left(\frac {45}{31}\right)

180°-55.44° [as \pi radian= 180°]

124.56° in the anti-clockwise direction.

(d) Vector diagrams for \vec A +\vec B and \vec A - \vec B has been shown  

in the figure(b) and figure(c) recpectively.

Vector \vec A - \vec B is in 3rd quadrant as calculated in part (c).

While Vector \vec A +\vec B=(24 \hat i +33 \hat j)+(55 \hat i -12 \hat j)

\Rightarrow \vec A +\vec B=79 \hat i +21 \hat j, which is in 1st quadrant as both the components are position has been shown in figure(b).

6 0
3 years ago
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