Answer:
2.The density of air increases and thendecreases as the sound wave passes.
Explanation:
Sound waves are mechanical waves, which consist of oscillation of the particles in the medium where the wave is transmitted through.
Sound waves are also longitudinal waves, which means that the direction of oscillations of the particles of the medium occurs in a direction parallel to the direction of motion of the wave (so, essentially back and forth).
Due to the nature of longitudinal waves, they create alternating regions of the medium where the density of particles are higher and lower. The former are called compressions, while the latter are called rarefactions.
Therefore, when a sound wave travels through the air, the density of one region of air continuously changes: compression first (high density), rarefaction then (lower density), then compression again, etc..
The velocity of the ball is 12.5 m/s
Explanation:
The velocity of the ball is given by the ratio between the distance covered by the ball and the time taken:

First, we calculate the distance covered. We know that the radius of the circle is
r = 0.450 m
And the length of the circumference is

The ball makes 25.0 revolutions, so a total distance of

In a time of
t = 9.37 s
So, its velocity is

Learn more about velocity here:
brainly.com/question/5248528
#LearnwithBrainly
Answer: concentration c = 25.2 g /(41.99 g/mol × 0.75 l)
Explanation: M(NaF) = 41.99 g/mol and amount of substance n = m/M.
Concentration c = n/V
Electrons are transferred sequentially between the two photosystems, with photosystem I acting to generate NADPH and photosystem II acting to generate ATP. The pathway of electron flow starts at photosystem II, which is homologous to the photosynthetic reaction center of R. viridis already described.
If the girl is also near the source of the sound, two alike sets of sounds will be heard.