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:
Squids = 450 - 490 nm (Moderate Frequency) (Blue)
Bees = 300 - 650 nm (Lower Frequency Bands)
Frogs = 280 - 580 nm (Very Low Frequency)
Explanation:
All of the above mentioned ranges are compared to that of humans.
I'm just surprised a little bit in the imagination that how these organisms see the world through their unique eyes. On the other hands, they are evolved like this just like we do so that may not be surprising enough. SIKE
Answer:
The difference is 7.6 grams.
Explanation:
In mathematics the difference of two numbers is express as the subtraction between them:

So to find out the difference between the two measured masses, a will be represented by 123.6 grams since is the bigger number, and b by 115.972 grams.
Therefore, it is get:

<u>Hence, the difference is 7.6 grams. </u>
The result of 7.628 will be expressed as 7.6 to have the correct number of significant figures.
Notice how that can be express in units of kilograms too since there is 1000 gram in 1 kilogram:
⇒ 
Acceleration = velocity/time
A= 3.5m/s/15s
A= 0.23m/s^2