a) The warning tag on a lawn mower states that it produces noise at a level of 9

Question

a) The warning tag on a lawn mower states that it produces noise at a level of 97.0 dB. What is this in W/m2?
? W/m2

b) What sound level in dB is produced by earphones that create an intensity of 7.50 ? 10-2 W/m2?
? dB

c) (a) By what factor is one sound more intense than another if the sound has a level 16.0 dB higher than the other?

(b) If one sound has a level 31.0 dB less than another, what is the ratio of their intensities?

d) 17 cars in a circle at a boom box competition produce a 130 dB sound level at the center of the circle. What is the average sound level produced there by each, assuming interference effects can be neglected?
? dB

Explanation / Answer

a) beta = 10*log*(I/Io)

97 = 10*log(I/10^-12)

I = 10^(9.7-12)

= 5.01*10^-3 W/m^2 <<<<<<<<----------------Answer

b) beta = 10*log(7.5*10^-2/10^-12)

= 108.75 dB <<<<<<<<----------------Answer

c)

beta2 - beta1 = 10*log(I2/Io) - 10*log(I1/Io)

16 = 10*log(I2/I1)

I2/I1 = 10^1.6

= 39.8 <<<<<<<<----------------Answer

b)
I2/I1 = 10^(-3.1)

= 7.94*10^-4

d)

130 = 10*log(7*I/10^-12)

130 = 10*log(I/10^-12) + 10*log(17)

130 = sound lvel of one car + 12.3

sound lvel of one car = 117.7 <<<<<<<<----------------Answer

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