29 September 2012

Puppy Linux saves me

Your computer is going to crash; are you prepared?

I had warnings. I kept getting that my computer was running low on tmp space. I would go and empty that directory, but I would still get that warning, so I should have known that something was amiss. However, I didn't have time to check things out; school was starting soon, so I was preparing for that. And, then it happened. I started the computer one day and I got stopped at the command-line. The computer suggested that I reconfigure Xorg which I did to no avail. Again, no time to dig deeper into the problem and I needed to check email. No problem. I grabbed the USB drive on which I had installed Puppy Linux several months ago, told the computer to boot via USB, and I was up and running and doing what I needed to do. I am writing this using Puppy. When I have time, I will use it to rescue my normal Linux installation.

What is Puppy Linux?

One of the results of the Linux and hacker (in the original sense) community is varieties of Linux called minimal distributions. They are designed to be stripped-down versions that can fit on a portable device and run without being installed on your computer. Some are developed to be rescue tools, but others try to fit as much as possible into a small package. Puppy Linux is an example of the latter. You can run it off a CD or a small USB flash drive. An old 1 gigabyte thumb drive is more than enough. Instructions on how to install are very easy to follow.

What do you get?

At first glance, you might not expect to get much from programs that take up only 100 megabytes of space. But you get a fully functional system. You get a web browser, word processing, picture editing, music playing, and everything you use on an everyday basis. You also get the ability to do file management on the files on your computer's hard drive, even if you can't start up your normal operating system. Afraid you are going to lose those irreplaceable photos from a wonky hard drive? You can copy them to another flash drive or to CD with Puppy. Need to edit a document for school? You can do it with Puppy. Need to replace a corrupted system file that you think is preventing you from booting up normally? Do it with Puppy. If all you do with Puppy is recover from a computer crash, it worth spending a couple of hours downloading and trying it out.

Save old hardware

 Do you have an older laptop or desktop that is running slow and now just sits in the basement. Give it new life with Puppy. Since load itself into your RAM memory, it runs very fast. Do you have an older family member or young student who just needs to do basic document preparation, e-mail, and web browsing? Install Puppy to the hard drive and they are good to go with the added benefit of not having to worry about viruses. Need something special? Check out the different varieties called Puplets made by members of the Puppy community to serve special needs and desires.

Given that more and more of our lives are dependent on computers that fail at inopportune times, you should be prepared. Puppy Linux can be a life-saver.

22 September 2012

What is your local acceleration due to gravity?

How much does gravity suck?

One of the ubiquitous labs in high school physics is a variation on the gravity lab, where students measure the local acceleration due to gravity.  Whether the method is with free-fall, a ramp , or a pendulum, this lab is probably the first time they have measured an important physical constant. I have my classes do the pendulum lab first with manual timing (see note below), and then with electronic timing. As a measure of how good their work has been, their result is compared to the best measure of the local acceleration. There are several on-line sites that will try to calculate an approximation for your location like the one at NGS, but you might live near an actual measurement site.

You can find the results of actual National Geodetic Survey measurements from a nearby station at this site.  My school is about a mile away from this site, so my students can compare their results to actual, professional results made at a site they can visit.

If you do live near such a site, a document like above might make such a measurement more real for your students.


I like to do the gravity-pendulum lab twice in my class, once with manual timing, and then with electronic timing. However, the real purpose of these labs is to have the students write formal lab reports.
For the manual timing one, I give no guidelines other than "You learned how to write one in chemistry." and "Have someone else, like your mother or father, read it before you hand it in." I want to see what they consider a good write-up. Of course, most give me a hastily thrown-together hack job, with no evidence of an outside reader. After I grade these, we have a discussion of how to make the writing better. They then have a chance to improve that skill with a redo of the lab, but with electronic timing. I tell them I expect not only much more precise writing, but much more accurate results.

18 September 2012

Using WinPlot (and a hidden feature)

Sometimes, you need to insert a simple graph or blank axes into an assessment.  Some might use the charting features in a spreadsheet such as Gnumeric or Excel, while others may use a graphing app built into their computer's OS.  However, for good customization, you need a plotting program.  I highly recommend the free program WinPlot, by Peanut Software.

WinPlot is a labor of love of Richard Parris at Phillips Exeter Academy.  He updates the program frequently and is very open to suggestions for improvement.  The program is very easy to use, runs without officially installing it onto a computer (you can run it from your own personal directory), and has a lot of useful features. It is my "goto" for inserting graphs and axes into my class documents.  This post will not attempt to be a tutorial on how to use WinPlot; one can be found at the main site.

The one "hidden"feature that got me excited today is a quick way to edit a WinPlot graph already in an editable electronic document.  For years, whenever I wanted to change the labels on a set of axes, I would open up WinPlot and either modify an already saved plot or create a new one with the wanted labels.  Today, I stumbled upon a shortcut.  Below is a graph that I had created in WinPlot, copied there, and then pasted into my word-processing program.

I want to change the label on the vertical axis.  By clicking on the image, I entered the edit mode, as shown by the corner marks.  And, then by clicking on the axis label, the textbox is selected for editing.

I can then change the label to anything I want without having to go back to WinPlot.

A time saver that I will use many times in the future.


While I have much praise for WinPlot, my one complaint about is that it is a Windows only program.  Whenever possible, I like to use cross-platform programs.  For publication-ready plots and graphs, I recommend GNUPlot, which is cross-platform.  GNUPlot is by itself a command-line program, but there are many GUI's available that are helpful (the Windows and Mac versions already has the GUI built in).  It is much more powerful program than WinPlot, and so can take some time to learn, but it will produce graphics that can be use in professional publications.  If you are looking for the Ferrari (but still free) of graphing programs, try GNUPlot. However, as powerful as GNUPlot is, it still can't do the above trick that WinPlot can.