Sound intensity is inversely proportional to the square of the distance between the source and the receiver.
That is
I = k/r^2
where
k = constant
r = radius
When r=1, the intensity is I₁ = k/1 = k
When r=3, the intensity I₂ = k/3² = k/9
Therefore
I₂ = I₁ /9
In decibels,
I = 10 log₁₀(I/I₀)
where I₀ = reference intensity
When r=1,
10 log₁₀ (I₁/I₀) = 270
When r =3,
10 log₁₀ (I₂/I₀) = 10 log₁₀ [(I₂/I₁)*(I₁/I₀)]
= 10 log₁₀ [(1/9)*(I₁/I₀)]
= 10 log₁₀(1/9) + 270
= 260.5
Answer: 260.5 dB (nearest tenth)
Answer:
Mass in science, is measured in the metric system using units such as kilogram (about 2.2 pounds)n which are a thousand grams, grams, centigrams (hundredths of grams), and milligrams (thousandths of grams). Mass is different from weight, Weight is a force.
Explanation:
hope that helps
Answer:
92.7 km
Explanation:
Since the magnetic field due to a solenoid is given by B = μ₀Ni/L where μ₀ = permeability of free space = 4π × 10⁻⁷ H/m, N = number of turns of solenoid, L = length of cardboard tube = 58 cm = 0.58 m, , i = current in wire = 2.5 A and l = length of wire.
So, N = BL/μ₀i
Since B = 2.0 kG = 2.0 × 10³ G = 2.0 × 10³ × 10⁻⁴ T = 2.0 × 10⁻¹ T = 0.2 T
So, substituting the variables into the equation, we have
N = BL/μ₀i
N = 0.2 T × 0.58 m/(4π × 10⁻⁷ H/m × 2.5 A)
N = 1.16 Tm/(31.416 × 10⁻⁷ HA/m)
N = 0.0369 × 10⁷ turns
N = 0.0369 × 10⁷ turns
N = 3.69 × 10⁵ turns
length of wire l = NC where N = number of turns and C = circumference of tube = πD where D = diameter of tube = 8.0 cm = 0.08 m
So, l = NC
= NπD
= πND
= π × 3.69 × 10⁵ turns × 0.08 m
= 0.9274 × 10⁵ m = 9.274 × 10⁴ m
= 92.74 × 10³ m
= 92.74 km
≅ 92.7 km
Wood Rots is the correct answer, as the wood begins to die
