signed in as DAWooo BAHMAN Help Physics 2110 003 Flipped 30 wave Power Sanding w
ID: 1296654 • Letter: S
Question
signed in as DAWooo BAHMAN Help Physics 2110 003 Flipped 30 wave Power Sanding waves Soun t Ear Dainage trama sma Firecracker previous 1 of 10 t Ear Damage from a Small Firecracker Learning Goal To understand how to convert between different sound intensity scales and how the decibel intensity of a sound changes with distance. The decibel scale is logarithmic in intensity: Bis 10log h- In this formula, la is a reference intensity, which for sound waves, is taken to be 10 12 w/m This constant must be used to convert a particular physical intensity into a sound intensity level measured in decibels, Once we know the sound intensity level (in decibels) at a certain reference distance from a sound source, the decrease of intensity with distance can be accounted for by subtracting the decibel value appropriate to the ratio of the new distance to the reference distance. In this problem you w Use the decibel scale analyze asmall firecracker that emits 1200 W of peak power, To avoid confusion, intensities denoted by I are units of per meter denoted are in decibels. Part A What is the peak intensity p in decibels at a distance ot 1 mtrom the firecracker? Express B in decibels to the nearest integer. B(1). dB Part BExplanation / Answer
Given
power=1200 W
Distace = 1 m
Area =4?r2
Intensity I= Power/Area
So
intensity I =1200/4?(1)2
I=95.4929 W/ m2
intensity in decibel ?= 10log(I/I0)
Given I0=10-12 W/m2
?=10 log(95.4929/10-12 )
?=10(log1012 +log 95.4929 )
?= 10(12+1.9799)
?=10*13.9799
?=139.799 db
?= 140 db (nearest integer)
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