Which of the two definitions of mass is the correct?
What's the difference between the five masses: inertial mass, gravitational mass, rest mass, invariant mass and relativistic mass?
Random place change in row with restrictions My floating point number has extra digits when I print it "SELECT *" why is it an antipattern On multiple questions here and on stack overflow i saw people saying in the comments and answers that select * from table is almost always an antipattern without any explaination why. Althrough I can sort of deduce why it is an antipattern. I may be looking over a detail that someone else with better understanding of the issue noticed.  So here is my question, why people say that select * is an antipattern. why can't i select two objects in edit mode?     I am trying to make a face from two different meshes but can't perform the action I have installed Linux Bash on Windows 10 (available from Microsoft), but I've forgotten my password.  I've searched for a solution but I only find suggestions that involve doing something before the system boots, like accessing recovery mode, but that will not work in this case as this Ubuntu is just an application within a Windows system and doesn't have its own boot process.  How can I reset my password? Acknowledgements outside of document environment How do I add an acknowledgements section (maybe not specifically \section) outside of (before) my document environment?  in my .cls, there is  \def\@acknowledge{} ... \def\acknowledge#1{\booltrue{@ack} \gdef\@acknowledge{#1}} ... \def\ackpage{ \chapter*{Acknowledgments} \@acknowledge \newpage }   but it seems that I find problems when I put newlines in the  \acknowledge{folks in here}  (see  ) arccot limit: $\sum_{r=1}^{\infty}\cot ^{-1}(r^2+\frac{3}{4})$ How to restart X Window Server from command line? How can I restart X Window Server from the command line?  I'd really like to be able to restart my GUI without having to do a full system reboot. What is rank deficiency, and how to deal with it? What are Extension Methods? What are extension methods in .NET?    EDIT: I have posted a follow up question at How to find historical airfares? Is there a way to find out how much it would have cost to buy a particular airplane ticket at some point in the past?    For example, how could I find out how much it would have cost to buy a one-way itinerary from airport A to airport B on October 1, 2011 for travel on November 1, 2011? I  want to download free app in my iPod touch device and i have the following doubts.  Kindly resolve me doubts.   when i try to download it asks my credit card security number. since i am trying to download free app , why do i need to provide my credit card security code? Will i be debited for downloading the free app from app store?   I cant able to find any information regarding this on apple.  Please provide me some references about this from apple and please resolve my doubts.  Thanks a lot. Are there Ubuntu security notices feeds for specific releases Let $been(x,y)$ denote "person x has been to place y."   Express “Every person has been to 2 or more places” using quantifiers and $been(x, y)$.  This one is completely stumping me. I'm sure that I haven't come across this kind of concept before, and can't wrap my head around how I would approach it. I suspect the quantifiers should be $∀x$, $∀y$, and that it may involve negating the statement "every person has been to one or zero places," but that's as far as I can manage to go. Any help greatly appreciated. Update from 14.04 to 16.04 failed with GPG error From : In calculus and other branches of mathematical analysis, an indeterminate form is an algebraic expression obtained in the context of limits. Limits involving algebraic operations are often performed by replacing subexpressions by their limits; if the expression obtained after this substitution does not give enough information to determine the original limit, it is known as an indeterminate form.    The indeterminate forms include $0^{0},\frac{0}{0},(\infty - \infty),1^{\infty}, \ \text{etc}\cdots$   My question is can anyone give me a nice explanation of why $1^{\infty}$ is considered to be an indeterminate form? Because, i don't see any justification of this fact. I am still perplexed. Let $a, b$ be elements of a group $G$. Suppose that a has order $5$ and that $a^3b = ba^3$. I want to show that that $ab = ba$.  Here is what I think:   We know that we have $a^1, a^2, a^3, a^4, a^5 = 1$. So, $a^4 = a^{-1}$ and $a^3 = a^{-2}$ and $a^{2} = a^{-4}$. Now,   $a^3b = ba^3$ then $a^{-2}b = ba^{-2}$ then $ba^2 = a^2b$ then $ba^{-4} = a^{-4}b$ then $a^{-1}b = ba^{-1}$ then multiply on the left and right by $a$ to get $ba=ab$. Is this correct or is there a simpler approach? Is Bran able to have children after his fall? The thing that made me ask this question was that most of Stark family are dead and Bran is now the "heir" to Winterfell. So I guess he should have children to succeed him, otherwise the Stark line will end. (I'm assuming Arya will not come back to Westeros and Rickon's fate is sealed, though I could be wrong.) I don't remember reading anything about it. I have been experiencing an issue that once I have a material created and looking the way I want it, I cannot seem to export it correctly with the textures mixed.  I don't know the correct words to use, but in blender I have the material created using the nodes editor, and I have placed two textures inside of there (one for the rock texture and one for moss, my object is a rock). When I export this model and import to Unity (the game engine I am using), I find a materials folder but the material inside of it does not have the textures assigned, it's just a plain white material?  How can I export my material from blender in a way that it will allow me to import it WITH TEXTURES into Unity? How can I "group by" and sum a column in excel? I'm trying to figure out how to "group by" values in an Excel spreadsheet.  Given the following example (this is an inventory sheet I use at my restaurant:)    At the far right of the spreadsheet there is a column named Cost of Goods Sold.  I would like to be able to come up with a total COGS figure for each Category.  Is this possible in excel? Moreover, I'd like to do it in a separate worksheet so that the first worksheet (what is pictured) isn't affected.  Any ideas?  Thanks!