The sound level of one person talking at a certain distance from you is 80 dB. If she is joined by 2 more friends, and all of them are talking (incoherently) at the same time as loudly as she is, what sound level are you being exposed to? a)

Explanation:

sound level scale is logarithmic which is given by the following formula

L = 10 log I / I₀ where I₀ = 10⁻¹² W / m² s

80 = 10 log I / 10⁻¹²

8 = log I / 10⁻¹²

I / 10⁻¹² = 10⁸

I = 10⁻⁴ W / m² .s

for three person the intensity becomes three times ie

3 x 10⁻⁴

L = 10 log 3 x 10⁻⁴ / 10⁻¹²

= 10 log 3 x 10⁸

= 10 ( 8 + log 3 )

= 10 ( 8 + .477 )

= 84.77 dB .

answer: the direction of the wind is expressed as the direction from which the wind is blowing. for example, easterly winds blow from east to west, while westerly winds blow from west to east.

explanation: