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
Do you see that blank, open space after the word "potential ..." ?
There's supposed to be a number there that actually tells us the value of the potential. Without that number ... and a lot more description of the whole scenario here ... there's no possible answer to the question.
Answer:
It includes earthwork, trenching, wall shafts, tunneling and underground
Explanation:
V₁(O2) = 6.50<span> L
</span>p₁(O2) = 155 atm
V₂(acetylene) = <span>4.50 L
</span>p₂(acetylene) =?
According to Boyle–Mariotte law (At constant temperature and unchanged amount of gas, the product of pressure and volume is constant) we can compare two gases that have ideal behavior and the law can be usefully expressed as:
V₁/p₁ = V₂/p₂
6.5/155 = 4.5/p₂
0.042 x p₂ = 4.5
p₂ = 107.3 atm