What is the air resistance for objects moving supersonically?
Air friction at supersonic velocities
Editing Gsettings unsuccesful when initiated from cron How is offside determined in football? The offside rule on the pitch is often unclear and called suddenly. How do I know if a player is offside? Once upon a time,  DISPLAY=:0.0 totem /path/to/movie.avi   after ssh 'ing into my desktop from my laptop would cause totem to play movie.avi on my desktop.  Now it gives the error:   No protocol specified Cannot open display:    I reinstalled Debian squeeze when it went stable on both computers, and I guess I broke the config.   I've googled on this, and cannot for the life of me figure out what I'm supposed to be doing.   (VLC has an HTTP interface that works, but it isn't as convenient as ssh.)  The same problem arises when I try to run this from a cron job. How to view CD key for a Steam game? I have purchased a game on Steam and can not find out the details of the file or purchase. How does one find their CD Key from a game purchased in Steam? Seeking documentation for {z}/{x}/{y} syntax in tilesource urls? Speaking of tilesource urls such as   http://{s}.tile.stamen.com/watercolor/{z}/{x}/{y}.png  is there any technical documentation or canonical reference for the curly braces syntax?  I'd specifically like to know what other things can be used in curly braces, and in which places, and how they work. How do we prove $n^n \mid m^m \Rightarrow n \mid m$? I'm not sure I've got this right. When proving $a^n \mid b^n \Rightarrow a \mid b$, can we do this indirectly? In short,  "Suppose $a$ does not divide $b$, this implies that $a^n$ does not divide $b^n$. But $a^n \mid b^n$, hence $a$ divides $b$."  How about $n^n \mid m^m \Rightarrow n \mid m$? Can we do this the same way? Validationengine jquery not working properly for localization Find the smallest integer $n$ greater than $1$ such that the last $3$ digits of $n^2$ are the same as the last $3$ digits of $n$. Find the smallest integer $n$ greater than $1$ such that the last $3$ digits of $n^2$ are the same as the last $3$ digits of $n$.  So far I've got $n^2 = 1000k + n$ which means $n^2 ≡ n \mod 1000$. I  don't know how to proceed since 1000 seems to be a bit high. If $|f(z)|\le |g(z)|$, can we say $f$ is constant? Let $f$ and $g$ be entire functions and $g(z)\neq 0$ for all $z\in \mathbb{C}$. If $|f(z)|\le |g(z)|$, can we say $f$ is constant?  Liouville theorem says that an entire bounded function is constant, but g is not given bounded here. So I think it should be false. What else can we say about $f$? There are so many questions on this website. There is so many questions on this website.  The former &quot;sounds right,&quot; but the contracted form of the latter does as well:  There's so many questions on this website.  Which is correct? Greatest comeback in 2nd leg match How can I show that $n! \leqslant \left(\frac{n+1}{2}\right)^n$? Show that $$n! \leqslant \left(\frac{n+1}{2}\right)^n \quad \hbox{for all } n \in \mathbb{N}$$  I know that it can be done by induction but I always find line where I do not know what to do next. Choosing coordinate system to use in South Africa? What are the principal datums and projections used in South Africa including the names of geodetic datums and their projections? Is there a keyboard shortcut to "unselect" in Windows Explorer? sed substitution with Bash variables in the street or on the street Create a tar archive split into blocks of a maximum size I need to backup a fairly large directory, but I am limited by the size of individual files. I'd like to essentially create a tar.(gz|bz2) archive which is split into 200MB maximum archives. Clonezilla does something similar to this by splitting image backups named like so:  sda1.backup.tar.gz.aa sda1.backup.tar.gz.ab sda1.backup.tar.gz.ac   Is there a way I can do this in one command? I understand how to use the split command, but I'd like to not have to create one giant archive, then split it into smaller archives, as this would double the disk space I'd need in order to initially create the archive. Let $F$ be a field. Why does $F[x]$ have infinitely many irreducible elements?   For the case F has characteristic 0  Then x-a is irreducible for all a $\in F$ since x satisfies no non-trivial relations in F.  Obviously this argument fails for a finite field since there are only finitely many a to choose from.  So how may I construct irreducible polynomials in a finite field?  I figure it must involve higher powers of x, maybe $x^n-a$ ? I'm looking to do a third-party assessment of the false-positive rate of a video classification algorithm. Since I have a lot of video I'm trying to do a power analysis to figure out exactly how much video I need to look through so that it is representative of all the video data at a given confidence interval.  The algorithm flags video sequences that have at least one cat in it, and I'm looking to evaluate the frequency of false positives on a new unlabeled test set. So I have tagged all the video that my algorithm has identified a cat in and now want to sample the tagged video sections and look through them manually to validate my model since looking through all of it would take too long! Note, I'm not looking to refine the model at this point, just assess it.  My null hypothesis is that the FP rate of the sample of video I watch is equal to the FP rate of all the video.   I think I can use this formula to determine the number of video sequences to view:    Here is my question: am I thinking through this formulation correctly? Since my model has a CV false positive rate of ~0.96, I figure I can use that as a reference. Can I use that for the null hypothesis proportion, p0? Or will that be p, the true proportion?    I've been using this online calculator:   I ask because when setting the parameters I have, I'm getting very small sample sizes, like less than 10 sequences to view. That can't be right. Server only reachable over VPN I have an Apache server running on a Raspberry P and it works just fine in the local network. And after forwarding port 80 and trying to connect using the public IP, Chrome says ERR_CONNECTION_REFUSED. But the strange thing is that I CAN reach the server when using VPN and using the same IP. What can I do?     -telnet 80.***.***.78 80      Trying 80.***.***.78...     telnet: connect to address 80.***.***.78: Connection refused     telnet: Unable to connect to remote host     -route -n      Destination     Gateway         Genmask         Flags Metric Ref    Use Iface     0.0.0.0         192.168.0.1     0.0.0.0         UG    0      0        0 eth0     192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0      -sudo netstat -lapute:              Active Internet connections (servers and established)     Proto Recv-Q Send-Q Local Address           Foreign Address         State       User       Inode       PID/Program name     tcp        0      0 *:http                  *:*                     LISTEN      root       6137        2051/apache2     tcp        0      0 *:ssh                   *:*                     LISTEN      root       6367        2249/sshd     tcp        0      0 pi.local:ssh            nmb.local:65535         ESTABLISHED root       8669        2565/sshd: pi [priv     udp        0      0 *:9949                  *:*                                 root       5918        1809/dhclient     udp        0      0 *:mdns                  *:*                                 avahi      6293        2184/avahi-daemon:     udp        0      0 *:54070                 *:*                                 avahi      6295        2184/avahi-daemon:     udp        0      0 *:bootpc                *:*                                 root       5946        1809/dhclient     udp        0      0 pi.local:ntp            *:*                                 root       6310        2200/ntpd     udp        0      0 localhost:ntp           *:*                                 root       6309        2200/ntpd     udp        0      0 *:ntp                   *:*                                 root       6304        2200/ntpd