A firecracker has been measured to have a sound intensity le

Solution

a)

Sound intensity level in dB is given by

B=10Log(I/I_o)

82 =10Log(I/10^-12)

=>10^8.2 =I/10^-12

I=1.585*10^-4W/m²

Area

A=4pi*r² =4pi*25² =7854 m²

Power released during explosion

P=IA =(1.585*10^-4)*7854

P=1.24 Watts

b)

=>120=10Log(I/10^-12)

I=10¹²*10^-12=1 W/m²

Since

P=IA

=>A=P/I =1.24/1 =1.24 m²

4pi*r²=1.24

r=0.314 m