As answered for your other question
A sound level of 90.0 dB90.0dB converted in units Wm^-2Wm−2 is
Let 90.0dB=xWm^-290.0dB=xWm−2
Implies that
10 log(x/(1xx10^-12))=9010log(x1×10−12)=90
=> log(x/(1xx10^-12))=9.0⇒log(x1×10−12)=9.0
Taking "anti "loganti log
=> x/(1xx10^-12)=10^9⇒x1×10−12=109
=> x=10^9xx1xx10^-12⇒x=109×1×10−12
=> x=10^-3Wm^-2⇒x=10−3Wm−2
Energy falling on eardrum ="Intensity"xx"Area"=Intensity×Area
=10^-3xxpi(0.500/2xx1/100)^2 =10−3×π(0.5002×1100)2
=1.9634xx10^-8W=1.9634×10−8W
Total energy falling on the ear drum in 77hours
=1.9634xx10^-8xx7xx3600=1.9634×10−8×7×3600
=4.948xx10^-4Wcdot s=4.948×10−4W⋅s
Since joule is also watt-second, therefore
Total energy falling on the ear drum in 77hours=4.948xx10^-4J=4.948×10−4J
