<span>A cold front separates a cold, dry air mass from a warm air mass.</span>
Answer:
The answer is β=0,85 rads
Explanation:
As the ladder is leaning against the building, we can imagine there´s a triangle where 20ft is the hypotenuse and 15ft is the maximum vertical distance between the ladder and the ground, it means, the leg opposite to β which is the angle we need
Let β(betha) be the angle between the ladder and the ground
We also know that 
In this case we will need to find β, this way:

Then β=48,6°
We also have that 2πrads is equal to 360°, in this way we find how much β is in radians:

then we find β=0,85rads
<span>Match the basic components of a nuclear reactor with their descriptions.
1. slows down neutrons
moderator - This is the substance that slows down fast neutrons and makes them slow neutrons which are easier to capture by the atomic nuclei so that the fission reaction can continue.
2. absorb emitted neutrons
control rods - These are rods made up of a substance that easily absorbs neutrons. Their purpose is to slow down or shut down the reaction.
3. mass of unstable atoms
nuclear fuel - The entire point of a nuclear reactor is the capture the energy released by the fission of unstable atoms. So this mass of unstable atoms is the fuel for the nuclear reactor.
4. concrete and lead enclosure
shield - This is the enclosure that prevents radiation from escaping into the general environment.
5. energy transfer medium
coolant - Since the purpose of a nuclear reactor is to generate usable energy, the coolant extracts heat from the fissioning core and that heat is generally used to boil water which in turn is used to operate turbines that power electrical generators.</span>
By the definition of wavelength, the answer is the letter D, the wavelength would decrease.
We can see in the diagram a wave motion.
A wave has some characteristics:
- Has an amplitude, the distance from 0 to the crest (highest point in the y-direction, point (3) in the figure) it would see in the figure as (2)
- Has wavelength, the distance between the crests.
- Has a trough, the lowest point in the y-direction.
Now, if we increase the distance of the crests, by the definition shown above, we will increase the wavelength.
Therefore, the answer is letter D, the wavelength would increase.
You can learn more about wave motion here:
brainly.com/question/22763521