The answer to this question is C. The reason why this is an incorrect statement is that the Doppler effect takes into account two moving objects. In this scenario, both the source and the listener are stationary to the frequency of the sound waves will not change due to the Doppler effect. For the other answers, the frequency of sound waves is not affected by nature of the medium. The distance between a sound source and listener does not alter the frequency of the sound wave. The frequency of the sounds waves remains the same to the listener.
This one is simple :)
use the equation F = ma and then re-arrange for a.
a = F / m
But there is a trick, so be careful. the question gives you wind resistance. Simply subtract the wind resistance from the thrust of the rocket to get the net force upward.

So,
Answer:
F= 0
Explanation:
This exercise we use Newton's second law,
F = m a
in this case as the speed is constant the acceleration is zero therefore the force is zero.
Change we can solve it using Newton's first law, which states that every vehicle remains still or with constant speed if there is no extensive outside acting on it
We see that with any of the two forms the sum of the applied forces is zero
∑ F = 0
1. Monophly - all descendants of an ancestral talon are grouped together (i.e. phylogenetic analysis should clearly demonstrate both monophyly and validity as a separate lineage).
2. Reasonable - with respect to evolutionary relevant criteria, i.e ecology morphology, or biogeography; DNA sequences are a consequence rather than a condition of divering evolutionary lineages