i have some physics questions.
If an infant can scream at a sound level of 111.0-dB measured at a distance 11.0-cm from their mouth, how far away should a parent stand so that the child can be seen but not heard? (The threshold of hearing is 0-dB, or equivalently I0 = 10-12-Wm-2.) Assume spherical symmetry for the dispersion of the sound wave energy (this is of course a bad assumption).
Answer km
How much power is the child putting in to screaming?
Answer
Answer=__________ W
We know that, decibel intensity is given by
Db = 10 log(I/Io)
111 = 10 log(I/10^-12)
11.1 = log I + 12
0.9 = log I
I = 10^0.9 = 7.94
7.94*0.11^2/R^2 = 10^-12
R = sqrt(7.94e12 *0.11^2)
= 310000 m
= 310 km
B) power = 7.94* 4 pi*0.11^2
= 1.207 W
i have some physics questions. If an infant can scream at a sound level of 111.0-dB...