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1 answer:
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Answer:
The intensity level in the room is 63 dB
Explanation:
To calculate the intensity of sound in the room, we use the equation of definition of decibels
β = 10 log (I / Io) (1)
With “I” the sound intensity and “Io” the threshold intensity 1.0 10⁻⁻¹² W/m²
To calculate the intensity we will use the initial data and remember the power of the emitted sound is constant, in addition that the sound propagates in three-dimensional form or on a spherical surface
I = P/A ⇒ P = I A
The area of a sphere is 4 π r², where I can calculate of 1
β/10 = log (I/Io)
I / Io =
I = Io
I = 1 10⁻¹² 10⁽¹⁰⁰/¹⁰⁾ = 1 10⁻¹² 10¹⁰
I = 1.0 10⁻² W
With this we can calculate the intensity for a distance of 20 m
I = 1.0 10⁻² / ( 4π 20²)
I = 2.0 10⁻⁶ W/m²
We have already found the intensity at the point of interest, so we can calculate the intensity in decibels at this point with equation 1
β = 10 log(2.0 10⁻⁶ / 1.0 10⁻¹²)
β = 10 log ( 2 10⁶) = 10 6.3
β = 63 dB
The intensity level in the room is 63 dB
Answer:
u= 20.09 m/s
Explanation:
Given that
m = 0.02 kg
M= 2 kg
h= 0.2 m
Lets take initial speed of bullet = u m/s
The final speed of the system will be zero.
From energy conservation
1/2 m u²+ 0 = 0+ (m+M) g h
m u²=2 (m+M) g h
By putting the values
0.02 x u² = 2 (0.02+2) x 10 x 0.2 ( take g=10 m/s²)
u= 20.09 m/s
