At a rock concert, the sound intensity 1.0 m in front of the bank of loudspeaker

Question

At a rock concert, the sound intensity 1.0 m in front of the bank of loudspeakers is 0.10 W/m2. A fan is 30 m from the loudspeakers. Her eardrums have a diameter of 8.4 mm.

Part A

How much energy is transferred to each eardrum in one second?

Express your answer in Joules using two significant figures.

At a rock concert, the sound intensity 1.0 m in front of the bank of loudspeakers is 0.10 W/m2. A fan is 30 m from the loudspeakers. Her eardrums have a diameter of 8.4 mm.

Part A

How much energy is transferred to each eardrum in one second?

Express your answer in Joules using two significant figures.

Explanation / Answer

we know the relation with sound intensity and distance,

l1 / l2 = (r2 / r1)^2

0.1 / l2 = (30 / 1)^2

l2 = 1.11*10^(-4) W/m^2

area of eardrum is

A = pi*r^2 = 3.14*(0.0042)^2

A = 5.53*10^(-5) m^2

power P = l*A

P = 1.11*10^(-4)*5.52*10^(-5)

P = 6.16*10^(-9) W

energy is

E = P*t

E = 6.16*10^(-9)*t

E = 6.16*10^(-9) J

answer

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