Why pressure is considered as scalar quantity?
Define Pressure at A point. Why is it a Scalar?
Which features of a wizard's familiar, if any, are considered magical? The  spell has a duration of instantaneous, which implies that the familiar itself is not an ongoing magical effect. However, the spell provides a number of ongoing features that are definitely supernatural:    The familiar disappears when it drops to 0 HP. The wizard can temporarily or permanently dismiss the familiar. The wizard can communicate with the familiar telepathically. The wizard can observe through the familiar's eyes and ears. The familiar can deliver touch spells on behalf of the wizard.   Which of these features are considered magical? For example, would any of them show up to a detect magic spell or be suppressed by an antimagic field? In addition, is my assumption above correct that the familiar itself is not considered magical? Do we ever get more information about the Entwives? During my recent re-reading of The Two Towers I was struck again by a question that has bothered me since I was a youngling: What on earth is up with the Entwives?  Treebeard says they went away in the distant past and just... got lost?  Did Tolkien ever make mention of them again, or is this one of those unsolved mysteries of Middle Earth? From the Cracks in time and space story arc it's known that if a TARDIS is blown up (possibly while in the Time Vortex) it rips creation itself apart. Also, from the Stolen Earth / Journey's End we learn the Daleks' masterplan which is subjugating creation itself via destroying it with the Reality Bomb (unfading Z-neutrino energy radiation).  In the Last Great Time War all sorts of temporal weapons were used and it's known that Daleks have the ability of time travel as well. Why didn't they use the Time Vortex back then to win the war once and for all via detonating a TARDIS while inside? How can I get a copy of a Canadian visa refusal letter? Which of these are acceptable? Is one preferable over the other?   "Chemically-deposited tourmaline is never periwinkle." "Chemically deposited tourmaline is never periwinkle."   Also, is the title to the this question asking what I'm trying to ask?  (I realize that there are other questions about hyphenation in similar contexts; I'm asking specifically about -ly adverbs.) A very quick question:   Is it correct to say "In case I won't be able to watch that"?  If it's acceptable to say that, what type of sentence is it?  UPDATE:  As a clarification, I want to say "Can you give me that in case I won't be able to have it later". Probably, it's more a supposition than a conditional. Encountering a FileSystemRights value that isn't defined in enumeration Set myself as owner of /etc with chown command now getting all kinds of errors I needed to edit a .config file (which I know for a fact is not creating these problems, just to clear that up) and it wouldn't let me save it, so I took ownership of /etc and all contents with the command chown -hR username /etc and that let me edit the .config file but now whenever I try to install any packages or use any sudo commands, it doesn't work  (I've checked for errors in the sudo file in sudoers.d and there was nothing wrong with that).   So how do I return it to the previous owner? Number of connected components of the complement of a compact Let $X$ be a connected, locally compact space and let $K$ be a compact subset of $X$. Is the number of connected components of the complement $X\setminus K$ finite? If it is not, are there some hypotheses over $X$ for finiteness of connected components? Does a non-abelian semigroup without identity exist? I've got a PHP script that needs to invoke a shell script but doesn't care at all about the output. The shell script makes a number of SOAP calls and is slow to complete, so I don't want to slow down the PHP request while it waits for a reply. In fact, the PHP request should be able to exit without terminating the shell process.  I've looked into the various exec(), shell_exec(), pcntl_fork(), etc. functions, but none of them seem to offer exactly what I want. (Or, if they do, it's not clear to me how.) Any suggestions? When is using the past perfect tense not necessary? Is it more natural to speak in simple past or past perfect when explaining past events to a friend? It seems like Americans use more simple past in everyday life than past perfect. I found this example online:     I had almost completed my essay when my computer suddenly crashed and I noticed that I had forgotten to save the document.   Is it wrong to say the following instead?     I was almost done with my essay when my computer suddenly crashed and I noticed that I forgot to save the document.   Maybe it's just my friends, but I rarely hear them speak in past perfect, so I'm really torn about using past perfect when it isn't necessary. I found Minecraft's marvelous large worlds extremely slow to navigate, even with a quad core and meaty graphics card.  I assume Minecraft's slowness comes from:   Java, as spatial partitioning and memory management are faster in native C++. Weak world partitioning.   I could be wrong on both assumptions. However, this got me thinking about the best way to manage large voxel worlds. As it is a true 3D world, where a block can exist in any part of the world, it is basically a big 3D array [x][y][z], where each block in the world has a type (i.e BlockType.Empty = 0, BlockType.Dirt = 1, etc.)  I assume that to make this sort of world perform well, you would need to:   Use a tree of some variety (//) to split all the cubes out; it seems like an oct/kd would be the better option, as you can just partition on a per cube level not a per triangle level. Use some algorithm to work out which blocks can currently be seen, as blocks closer to the user could obfuscate the blocks behind, making it pointless to render them. Keep the block object themselves lightweight, so it is quick to add and remove them from the trees.   I guess there is no right answer to this, but I would be interested to see peoples' opinions on the subject.  How would you improve performance in a large voxel-based world? How to apply a modifier in V2.9+ Why I can't apply mirror modifier? Here's screen How can I do case insensitive string comparison in Python?  I would like to encapsulate comparison of a regular strings to a repository string using in a very simple and Pythonic way. I also would like to have ability to look up values in a dict hashed by strings using regular python strings. Get index of each capture in a JavaScript regex Been trying to find graphic novel for decades - at least I think it's a graphic novel Basic mathematical induction regarding inequalities Why does nothing show up in the Compositing tab? I am trying to follow Blender Guru's beginner tutorial. He went to the Compositor tab and was using it to Denoise an image but when I got there, no nodes show up. Can you guys help? How to deal with cross-thread access exceptions?