Answer:
r₂ = 0.2 m
Explanation:
given,
distance = 20 m
sound of average whisper = 30 dB
distance moved closer = ?
new frequency = 80 dB
using formula

I₀ = 10⁻¹² W/m²
now,



to hear the whisper sound = 80 dB



we know intensity of sound is inversely proportional to square of distances



r₂ = 0.2 m
Mass = 0.201kg
Energy = 15J
temperature change = 10C
Energy(E) = mass(m) × specific heat capacity(c) × temperature change(θ)
we can rearrange this to make specific heat capacity the subject
c =

c =

c =7.46268657
Energy of the waves are redistributed to form a resultant wave with amplitude given by the summation of individual wave's amplitude.
<span>If the two waves are of same frequency, speed and amplitude and travelling in opposite direction den stationary waves are form.</span>
32,100 Millimeters
3,210 Centimeters
3.21 Decameters
Hope It Helps
The S.I. unit for the measure of the pressure is the Pascal (Pa). 1 Pascal corresponds to

We can convert the number given by the problem into Pascal:

And since

, we have