What is the mechanism of a jackscrew?
Calculating the force required to lift a weight with a screw
Is the op-amp inverting or non-inverting? I am studying the function and characteristic of an op-amp to build a line-following robot with the schematics below. However, in many tutorials, the way to differentiate an inverting and non-inverting op-amp is by looking at the connection to ground via the inverting or non-inverting terminal.  However, in the schematics, the op-amp is considered to have connections to ground, thus in this case, how do I differentiate it then?  I may have understood the whole concept wrongly. Pls help!    EDIT: Please ignore the switch as it may have been drawn wrongly by the supplier. What causes a force field to be "non-conservative?" Why is AES considered to be secure? The security of RSA is based on the integer factorization problem, which is a very well defined and understood mathematical problem. This problem must be solved in order to fundamentally break RSA.   What about AES (and others based on the same idea)? Why is it difficult to break? Is there any mathematical principle that ensures its security? What is a concise function that formats a (String) decimal into a currency format in Apex? Importing users that will be installed by programs Read data from Excel file in Objective-C (iPhone) Change citation conjunction from "and" to "i" How can I change the citation conjunction from english "and" to catalan "i"?  Otherwise  Author = {Kirk, D. and MacPhail, A.},   would get cited as (Kirk and MacPhail, 2002) when it should be (Kirk i MacPhail, 2002).  When there are more than 2 authors I get et al. which is fine.  I've seen  and  which do not work with apalike style.  Also, I'd rather not use biblatex if possible. Is there a way to prove that the order of an element in a Group divides the order of the Group, WITHOUT USING LAGRANGE'S This is a very easy fact we use in Group Theory,  But somehow, I wondered that whether there may be another way (other than Lagrange's Theorem) to prove that the order of an element divides the order of Group.  I attempted to go on the term "exponent" of the Group (just assume that G is a Finite Group), which we may define the least common multiple of orders of elements in G. But this exponent divides $|G|$, since the order of each element divides $|G|$. So it became a little paradox.   Shall I think that; before teaching this fact in a Course, one should teach about Lagrange's first? Differentiability implying continuity Theorem: If $f$ is finitely differentiable at $c$, then $f$ is also continuous at $c$.  But according to the definition, for a function to be differentiable at $c$, it need not even be defined at $c$, just that it should have a finite value in the vicinity of $c$.    My question: If function is not defined at $c$, how can it be continuous at $c$?  For example, say we have a straight horizontal line function which is broken at $x=1$, the function is defined at all the points except $x=1$, it has a finite value at all the points except $x=1$, since it is having a value in the nearby region of $x=1$ we say that it is differentiable at $x=1$ but can we say that it is continuous at $x=1$? How to integrate $\int_0^{\infty} \frac{e^{ax} - e^{bx}}{(1 + e^{ax})(1+ e^{bx})}dx$ where $a,b > 0$. Why does aptitude give me intel-microcode upgrades when I have an AMD processor? I have a Supermicro AS-2022G-URF (H8DGU motherboard) with 2 AMD Opteron 6272 16C/16T 2.1GHz and an LSI MegaRAID SAS 2108 RAID controller currently running Ubuntu Server 14.04 LTS (scheduled to be upgraded to 16.04 this summer). Several times over the last year, when I have done aptitude update/upgrade, the intel-microcode package has shown up as one of the packages that will be installed. Since this server has AMD processors, not Intel, Why does aptitude offer this package? Is it in any way necessary for other reasons? Any ill effects from going along with aptitude on this? I want to prove that every real polynomial of odd degree has at least one real root, using  the intermediate value theorem.  Let $P(x) = x^{2n+1} + a_n x^{2n} + . . . + a_0$ for each $a_i \in \mathbb{R}$ and $n \in \mathbb{N}$.  By the fundamental theorem of algebra I know that $P(x)$ has exactly $2n+1$ complex roots, so  $P(x) = (x+r_1)(x+r_2) . . . (x+r_{2n+1})$ for each $r_i \in \mathbb{C}$  I do not know how to complete this but I do know that, at some point, I probably have to show that each root with imaginary part non zero has to come in conjugate pairs, and since $2n+1$ is odd there is at least $1$ root that is imaginary part $0$ and thus real. How do I stop friends from getting notifications about what I do on Facebook? Friends and family (who are not in my Close Friends group) are getting notifications when I post or like something on Facebook. How do I stop this? I have an external HD which used to be my TimeMachine drive. I got a different drive for that, so I want the original drive back as an external on my Windows box, but it has this random 200 MB partition labeled as EFI System Partition. How do I get rid of this? "In and of itself" is a phrase I find myself using all the time. But in and of itself, the phrase "in and of itself" has no meaning. That is, the individual words don't seem to contribute to the whole meaning of the phrase. I make heavy use of screen's "log" command to log the output of a session to a file, when I am making changes in a given environment. I searched through tmux's man page, but couldn't find an equivalent. Is anyone aware of a similar feature in tmux, or do I have to write my own wrapper scripts to do this?  EDIT: I'm aware of 'script' and other utilities that allow me to log a session. The reason that screen's functionality is so useful is the ability to define a logfile variable which uses string escapes to uniquely identify each session.  e.g. I have a shell function which, given a hostname, will SSH to that host in a new screen window and set the window title to the hostname. When I start a log of that session, it is prefixed with the window title.  If this functionality doesn't exist in tmux, I'll have to create a new set of shell functions to set up 'scripts' of sessions I want to log. This isn't hugely difficult, but it may not be worth the effort given that screen does exactly what I need already. If $f:[a,b]\to \mathbb{R}$ is continuous and nonnegative and $\int_a^b{f}=0$, then $f(x)=0$ for all $x\in [a,b]$ Possibility of making dark energy equivalent with dark matter Why do ICs have NC (No Connection or No Function) pins? bash: adduser: command not found on centOS I installed CentOS 5.5 on my VMWare 8 recently and I am trying to add a new user on the system. I am unable to add the user unless I use su - option. I believe it has to do something with path not set properly.  I updated the path and here is what it looks like  /usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/home/uone/bin:/sbin   I believe the command is in /sbin dir which is already a part of path. Can anyone suggest me what else I might be missing?