To solve this problem we will apply the concepts related to the Doppler effect. The Doppler effect is the change in the perceived frequency of any wave movement when the emitter, or focus of waves, and the receiver, or observer, move relative to each other. Mathematically it can be described as,

Here,
= Frequency of Source
= Speed of sound
f = Frequency heard before slowing down
f' = Frequency heard after slowing down
v = Speed of the train before slowing down
So if the speed of the train after slowing down will be v/2, we can do a system equation of 2x2 at the two moments, then,
The first equation is,



Now the second expression will be,



Dividing the two expression we have,

Solving for v, we have,

Therefore the speed of the train before and after slowing down is 22.12m/s
Answer: The correct answer is "trumpet".
Explanation:
Resonance occurs when the applied frequency on the object is equal to the natural frequency of the object.
Wind instruments use resonance in the air column to amplify the sound. It makes the sound louder. Sound is produced by using lips or vibrating reeds or buzzing sound into the mouthpiece.
Therefore, resonance in air column is used in trumpet musical instruments.
Answer:
smaller one
Explanation:
even though he is moving quicker doesn't mean he will be packing more force in the collision
Answer:
Closely fits into the connector.
Explanation:
It's one of the steps used for the splicing of aluminium conductors in the underground connections. Where we do the strip insulation to splice the conductors by using compression type connectors.
You are true, Stokey. The correct choice is<em> (c)</em>.
If you think about it a little bit more, you'll realize that "side to side" is also a horizontal motion.
Anyway, the question told us that we're only talking about 2 dimensions. Well, the The measurements in the 2 dimensions are the x and the y . If there were a z measurement, that would be the 3rd dimension.