Answer:
<u>because of the doppler effect</u>
Explanation:
<em>Remember</em>, the doppler effect refers to the changes in sound (frequency of sound) observed by a person who is in a position relative to the wave source.
In this example, we notice as the train comes closer to the boy, the sound becomes louder also increasing the pitch slightly, the doppler effect sets in when the train passes the boy because the boy notices a decrease in the pitch of the moving train.
We learn from the change in the observed sound of the train that the frequency of the sound is determined by the distance of the observer from the wave source.
In other words, the closer the source of the sound to the observer; the faster it travels to the observer, however, the farther it is; the lesser it is; the greater the sound heard.
You should select Choice-4 .
Answer:
It's probably the Redshift and Blueshift
Explanation:
The light shifting towards shorter or longer wavelengths as objects in space (stars or galaxies) move closer or farther away from us. This phenomenon is known as the Redshifts and Blueshifts. The concept indicates us that the Universe is expanding.
Hope this helps you!
Bye!
Answer:
1.60 g
Explanation:
From the attached file below:
we can deduce that:

The distance traveled by 2 s will be:
x = vt
x = 20 m/s × 2 s
x = 40 m
The length is quarter of the circle with radius r,
so; if 2 πr = 4 x
Then radius (r) will be:

r = 25.5 m
The centripetal acceleration can be expressed as:

so;

a = 15.7 m/s²
the magnitude of the acceleration experienced by your unfortunate passengers in terms of acceleration due to gravity is then determined by the equation:



∴ The magnitude of the acceleration experienced by your unfortunate passengers during the turn = 1.60 g
Answer:
D.N.A
Explanation:
The d.n.a is where all the heriditary information is stored.