Answer:
active solar heating systems use solar energy to heat a fluid either liquid or air and then transfer the solar heat directly to the interior space or to a storage system for later use. If the solar system cannot provide adequate space heating, an auxiliary or back-up system provides the additional heat.
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That is because there are other forces like the friction forces that apply differently on both of them. The frictional forces applied to the sled are smaller than they are on the father, for example, so it's possible for him to pull it.
It’s A.Longitudinal. Tell me if I’m right
Answer:
Explanation:
In order to answer this problem you have to know the depth of the column, we say R, this information is important because allows you to compute some harmonic of the tube. With this information you can compute the depth of the colum of air, by taking tino account that the new depth is R-L.
To find the fundamental mode you use:

n: mode of the sound
vs: sound speed
L: length of the column of air in the tube.
A) The fundamental mode id obtained for n=1:

B) For the 3rd harmonic you have:

C) For the 2nd harmonic:

Well velocity is a vector quanity and we can brake vectors in to verticle and horizantal componontes threw these two formulas Vcostheta=Vx and Vsintheta=Vy