Rain drops fall on a tile surface at a density of 4638 drops/ft2. There are 17 tiles/ft2. How many drops fall on each tile? Answ
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Answer:
<u>Part A</u>
I = 1.4 mW/m²
<u>Part B</u>
β = 91.46 dB
Explanation:
<u>Part A</u>
Sound intensity is the power per unit area of sound waves in a direction perpendicular to that area. Sound intensity is also called acoustic intensity.
For a spherical sound wave, the sound intensity is given by;
Where;
P is the source of power in watts (W)
I is the intensity of the sound in watt per square meter (W/m2)
r is the distance r away
Given:
P = 34 W,
A = 1.0 cm²
r = 44 m
The sound intensity at the position of the microphone is calculated to be;
I = 0.0013975 W/m²
≈ I = 0.0014 W/m² = 1.4 × 10⁻³ W/m²
I = 1.4 mW/m²
The sound intensity at the position of the microphone is 1.4 mW/m².
<u>Part B</u>
Sound intensity level or acoustic intensity level is the level of the intensity of a sound relative to a reference value. It is a a logarithmic quantity. It is denoted by β and expressed in nepers, bels, or decibels.
Sound intensity level is calculated as;
β dB
Where,
β is the Sound intensity level in decibels (dB)
I is the sound intensity;
I₀ is the reference sound intensity;
By pluging-in, I₀ is 1.0 × 10⁻¹² W/m²
∴ β
β
β = 91.46 dB
The sound intensity level at the position of the microphone is 91.46 dB.
Mass of the bird(m) = 150 g = 0.15 kg
Speed (v) = 10 m/s
Kinetic Energy = = 7.5 J
Altitude (h) = 15 m
Gravitational Potential Energy = (0.15)(9.81)(15) = 22.0725 J
Mechanical Energy = Kinetic Energy + Potential Energy = 7.5 + 22.0725
= 29.5725 J