Answer:
<h2>A. a spring & B. a well dried into an aquifer.</h2>
Answer:
About the universe, The problem isn't just that the sky has billions of stars to search but there are also billions of frequencies.
Answer:
total stretch of the double-length spring will be 20 cm
Explanation:
given data
length x1 = 10 cm
mass = 1 kg
mass = double = 2 kg
to find out
the total stretch of the double-length spring will be
solution
we can say here spring constant is
k = mg ............1
k is spring constant and m is mass and g is acceleration due to gravity
so for in 1st case and 2nd case with 1 kg mass and 2 kg mass
kx1 = mg .........................2
and
kx2 = 2mg ........................3
x is length
so from equation 2 and 3



x2 = 20
so total stretch of the double-length spring will be 20 cm
<h2>Answer: Radio waves </h2><h2 />
Radio waves are a type of electromagnetic radiation with wavelengths between 10 m to 10,000 m. In the electromagnetic spectrum this wavelength is longer than infrared light and therefore, it goes beyond the visible spectrum.
This type of electromagnetic waves is very well reflected in the ionosphere, the layer of the atmosphere through which they travel directly or using repeaters.
In addition, they are very useful to transport information, being important in telecommunications. They are used not only for conventional radio transmissions but also in mobile telephony and TV.
It should be noted that since radio signals have large wavelengths, they can be diffracted around certain obstacles, such as hills and mountain ranges, preventing the signal from reaching its destination.
Therefore, the correct option is C.