Answer: Δβ (dB) = -13.1dB
Explanation:
The intensity of sound is inversely proportional to the square of the distance between them.
I ∝ 1/r²
I₁/I₂= r₂²/r₁² .....1
When the listener increases his distance from the source by a factor of 4.49.
Then,
r₂/r₁= 4.49
From equation 1
I₁/I₂ = (4.49)²
I₁/I₂ = 20.16
I₂/I₁ = 1/20.16
The change in sound intensity in dB can be given as
Δβ (dB) = 10 log(I₂/l₁) = 10log(1/20.6) = -13.1dB
50km / 2.5 = 20 km per hour
It would be b. anemometer. it measures the speed of wind or any current of gas.
Gas always expands or contracts to exactly fill whatever you put it in.
So to measure the volume of a gas, just measure the volume of the jar, the tank, the bottle, the can, or the balloon that the gas is in.
