To develop this problem we will apply the concepts related to Sound Intensity. This can be defined as the power carried by sound waves per unit area in a direction perpendicular to that area. Mathematically it can be written as,

= Level Difference
n = Number of equal loud sound sources
n = 15
Therefore replacing we have,

Therefore over 100dB the total difference intensity level would be

Here,



The intensity level generated by one engine is

Answer: C. They are regions in which strong magnetic fields make it difficult for fresh supplies of hot, ionized gas to reach the photosphere
Explanation:
Sunspots appear dark because they are regions in which strong magnetic fields make it difficult for fresh supplies of hot, ionized gas to reach the photosphere.
Sunspots are typically cooler than their surroundings. For example, the temperature of a large sunspot can be about 4,000 Kelvin which is lower than the temperature of the photosphere around it which is about 5,800 Kelvin.
Answer:
Tuberculosis
Explanation:
Tuberculosis is a disease of lower respiratory system because it's affect the lungs and the voice box . It is a bacteria disease that affect the lungs and it is very contagious. It can spread rapidly to the brain and spine. Most times people with tuberculosis did not show symptoms but when there is symptoms,the symptoms include cough with blood, night sweats, fever e t.c.
Answer:
d = 2021.6 km
Explanation:
We can solve this distance exercise with vectors, the easiest method s to find the components of the position of each plane and then use the Pythagorean theorem to find distance between them
Airplane 1
Height y₁ = 800m
Angle θ = 25°
cos 25 = x / r
sin 25 = z / r
x₁ = r cos 20
z₁ = r sin 25
x₁ = 18 103 cos 25 = 16,314 103 m
= 16314 m
z₁ = 18 103 sin 25 = 7,607 103 m= 7607 m
2 plane
Height y₂ = 1100 m
Angle θ = 20°
x₂ = 20 103 cos 25 = 18.126 103 m = 18126 m
z₂ = 20 103 without 25 = 8.452 103 m = 8452 m
The distance between the planes using the Pythagorean Theorem is
d² = (x₂-x₁)² + (y₂-y₁)² + (z₂-z₁)²2
Let's calculate
d² = (18126-16314)² + (1100-800)² + (8452-7607)²
d² = 3,283 106 +9 104 + 7,140 105
d² = (328.3 + 9 + 71.40) 10⁴
d = √(408.7 10⁴)
d = 20,216 10² m
d = 2021.6 km