here is my relatively broad question: how does the temperature and density of a medium effect the speed at which sound travels through it?   Now I shall elaborate:  it is my understanding that there is some sort of ratio between these two factors that determine the speed of sound in the medium.   from this, I assume that sound travels faster in objects that have a higher temperature (due to atoms/molecules having more energy and hence being more inclined to transfer energy more quickly in order to assume its former energy state and become more stable) and a higher density (which I can only assume to be because the particles  are closer together and so somehow travel faster because of this, however, couldn't one also say that the opposite is true because there is less obstruction to block the waves? this is a point of confusion for me, help would be appreciated).  is there some sort of relationship or equation that relates the three factors and are there any other factors that determine the speed of sound in an object (eg. elastic properties of the medium)?  is there a value for this ratio that maximises the speed of sound (ie. some sort of linear constant) and is the relationship between speed and temperature and speed and density linear? if not what is it?  finally, with regard to the equations V=λ/T V=fλ and T=1/f where T=period, is the speed (velocity) of sound also dependent on the frequency and wavelength of the sound waves, or is it the other way round in which the frequency and wavelength are dependant on the velocity of the wave which is in turn dependant on other factors such as temperature and density? of course if the latter is true, what decides how the given product of frequency and wavelength is factored into individual components?
I was reading a textbook. I found that it was mentioned the speed of sound increases with increase in temperature. But sound is a mechanical wave, and it travels faster when molecules are closer.   But an increase in temperature will draw molecules away from each other, and then accordingly the speed of sound should be slower. How is it possible that the speed of sound increases if temperature increases? What is the relation of speed of sound and temperature?
I read in a CSV file for linking to a .shp file.   All the variables that are just numbers came in as text.   How do I change the text variables to numeric in QGIS? Don't show the edit option when I can't really edit (mobile apps) Currently in both  and  when viewing a post on a site where you don't have full edit privilege  (and not your own post) you can still see edit option in the actions menu:        So I choose it, invest time in editing the post, click "Submit".... and greeted with the dreaded "Account is not allowed to suggest edits" message: (and the edit is lost for good, no draft)        Can the "Edit" option be removed from the menu if I don't have edit privilege on the post, at least until suggested edit will be supported in the apps? What is hardware enablement (HWE)? I see the  package as part of the kernels you can install in Ubuntu.  What is hardware enablement (HWE)? A cannonball is launched from a point 100 m above ground, at a speed of 20 m/s. This is modelled by the equation $h(t)=-4.9t^2 +20t +100$ The speed of sound (of the cannonball is) 380m/s If a person sitting directly underneath the cannonball runs as soon as they hear the sound do they escape the cannon? My main question is &quot;$y=-380x+100$&quot; the correct equation to model the cannon's sound? How to create a function to sum the required multiple column I have a scenario where i want to sum the multiple column   The data in the file is :  ID|NAME|SAL|COST|PER|TAG  1|A|10|10|20|10|  1|B|10|15|20|10|  1|C|10|17|25|80|  1|D|115|110|20|100|  1|E|10|10|10|10|   i want sum of COLUMN - SAL | COST | PER | TAG   one i did with simple command but how to do by creating function  awk '{FS="|"}{s+=$3}END{print s}' file.txt   The function should be parameterised so that when i pass column name it should calculate sum for that column   The sum column's may differ. their may be requirement like only two column sum needed then it should take the two column names and process the sum for that Show the expected number of packets to buy to collect a whole set of minifigures Get tax deduction for expensive car expense Should I get the +2 bonus twice for suggesting a tag wiki? Kinematic Viscosity How many injective functions $f:[1,...,m]\to{[1,...,n]}$ has no fixed point? $(m\le n)$ How can I prove that if $\gcd(a, b) = 1$, then $\gcd(ab, c) = \gcd(a, c) \times \gcd(b, c)$?  By eea there exists $ax+by=1$ from $\gcd(a,b)=1$ so a and be are co-primes there also exists $dk=a$ and $dj= b$ where $d=\gcd(a,b)=1$ this is all the information I have gathered from the question but I dont know how to approach and solve it. Can anyone help explain to me how to arrive at the answer? Thanks! White space below footer The computed moments of log normal distribution can be found . How to compute them? Reason for the discreteness arising in quantum mechanics? What is the most essential reason that actually leads to the quantization. I am reading the book on quantum mechanics by Griffiths. The quanta in the infinite potential well for e.g. arise due to the boundary conditions, and the quanta in harmonic oscillator arise due to the commutation relations of the ladder operators, which give energy eigenvalues differing by a multiple of $\hbar$. But what actually is the reason for the discreteness in quantum theory? Which postulate is responsible for that. I tried going backwards, but for me it somehow seems to come magically out of the mathematics. Export File Dialog in Blender 2.80 How can I get bring up a popup file browser in Blender 2.80 invoked by a button click in my addon, to define the name and location of a file to be exported?  In Blender 2.7x, I did this via the context window manager in the invoke function, but it is very possible that this hasn't been the preferred method for years, as I'm not finding useful documentation when I search for how to update this.  class MYTOOL_OT_write_data(bpy.types.Operator):     bl_idname = "mytool.write_data"     bl_label = "Write data file"      directory: bpy.props.StringProperty(subtype="FILE_PATH")     filename: bpy.props.StringProperty(subtype="FILE_NAME")      def invoke(self, context, event):  # 2.7x method         WindowManager = context.window_manager         context.window_manager.FILEBROWSERect_add(self)  # &lt;-- error here         return{"RUNNING_MODAL"}      def execute(self, context):         directory = self.directory         filename = self.filename         # Write csv data file using normal python functionality         return{'FINISHED'}   In Blender 2.80, I am getting the error "AttributeError: 'WindowManager' object has no attribute 'FILEBROWSERect_add'".  Thanks for your help.    UPDATED SOLUTION based on brockmann's solution below.  The trick is to use the ExportHelper util (which existed long before Blender 2.80):  from bpy_extras.io_utils import ExportHelper  class MYTOOL_OT_write_data(bpy.types.Operator, ExportHelper):     bl_idname = "mytool.write_data"     bl_label = "Write data file"      filename_ext = ".csv"  # ExportHelper mixin class uses this     def execute(self, context):         filepath = self.filepath         # f = open(filepath, 'w')         # f.write(stuff)         # f.close()         return{'FINISHED'} What are Vertex and Pixel shaders? There has been a trend now two persons downvote it then it goes on like that. So let there be down voting but do not display the downvotes till the user votes on it. Else the user reads it with an impression that the question is not good.  Am I missing something? problems installing mathtools There have been a few questions regarding installing this package in the past, but they now seem to be out of date. I'm using MiKTeX 2.9 and TexMaker. When I try \usepackage{mathtools} in TexMaker it will try to install the package for me but will fail. I took the advice given in this thread:   As suggested I tried installing the mh package using the MiKTeX Package Manager, unfortunately I get the "unknown archive size" error, which I have read means that the package no longer exists. Another thread (lost the link) said you can use the MiKTeX Package Manager to directly install mathtools, however I do not see mathtools listed anywhere in the MiKTeX Package Manager...   So I ask, is the package under a different name? Are there any other ways to install this package? After a brief discussion with @MonicaCellio (In the comment) - It has come to my attention that perhaps I chose the wrong words to describe my original idea (In the edit history). When I wrote "social features" I was actually suggesting an alternative way to for users to share their knowledge using a new type of post and articles and not just by questions and answers.   The basics of my idea was to allow users to write articles on topics relevant to the community on the SE websites just as any answer posted is expected  to be too. Allowing users to write their own content (I.E posts/articles/etc..) will be granted as a privilege for advanced users so that not anyone could write stupid things, users that will write content must be established and well-familiar with the rules of SE.   I know anyone can start a blog, but it's require frequent maintenance and content updates, while writing on SE ensure that it addressed to a large, well-established community, with a similar fields of interest.  Posts writing will follow the same guidelines as asking and answering questions does, but it will provide an alternative for users that are mostly answering specific questions, as a new method to contribute to the community.   By writing, one may also reveal more about their personality, wit, way of thinking, ETC. That's when the "social" takes place - You'll also have "authors" and not just "users" you can remember by their catchy name, but people that you can remember by the field of interest they are writing content about.   They key points will be:    Users will be able write rich content with advanced WYSIWYG HTML editor, content that doesn't require a question to answer, but that is still relevant to the SE website it is writing on. Users will be able to Upvote/Downvote other users posts. Posts will be listed on their author profile, so it will not just show the activity, but additional layer of user generated content. Popular posts with high reputation could be associated to tags making the information of tags richer with user generated content Users will be able to include links in answers not only to other questions, but also to posts. User will be able to comment on post to allow the author to correct and improve it. It will improve the interaction and offline discussions (Which are prohibited when it come to long discussions on questions and answers). I believe that users will be happy to share their own tutorials, tips and tricks - Because they are already doing so when answering questions, but before the can start, they'll have to earn enough reputation to ensure that only high profile users will be able to write high profile content, and not just any rubbish. It will provide another type of method for voting and getting earning reputation Users will be able to include content in their CVs on SO Jobs.  Opportunity to earn some new badges.   So it's a Mega feature request and it require some detailed design work, but I do think that it will invite a new type of activity for users on SO (and the rests of the sites of-course). Given $|z|&lt;1$ with $z \in \mathbb{C}$ prove $\lim_{n \to \infty} z^n=0$.  My attempt given $\epsilon &gt;0$ we wish to show that there exists $\delta &gt;0$ such that $n&gt; \delta$ means $|z^n-0| &lt; \epsilon$.  For $n \in \mathbb{N}$. We have $|z^n|=|z|^n$. We wish $|z|^n &lt; \epsilon$. This means,  $$n \ln |z| &lt; \ln \epsilon$$  But because $\ln |z|&lt;\ln 1=0$ dividing both sides by $\ln |z|$ gives:  $n&gt; \frac{\ln \epsilon}{\ln |z|}$  So that's what we choose for $\delta$.   My question is is how can we get away from the assumption that $n \in \mathbb{N}$. Or is this correct even with the assumption?