<span>D. price ceiling
</span><span>This is a government regulation that establishes a maximum price for a particular good.</span><span>
</span>
Gravity if I’m not mistaken
When air<span> particles bunch up, it's </span>called<span> a compression-rarefaction.
When the </span>particles spread apart<span> its </span>called<span> a rarefaction.
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This depends on whether the pipe is closed or open ended.
The fundamental frequency of a pipe is the simplest, smallest portion of a wave that can fit into a pipe. At the open end of a pipe, there is always an antinode - an area with maximum air movement.
If it is an open ended pipe, there is an antinode at each end, meaning that the length of the pipe is equal to 1/2 <span>λ
</span>. Manipulating the formula <span><span>v=fλ</span>
</span> to solve for the fundamental frequency leaves us with <span><span>f=<span>v/<span>2L</span></span></span>
</span> in an open ended pipe.