[SEL] OT: Physics Help & error correction

[John Neth]

You are showing your age and a problem with US science.  Newtons and m/s/s.

In physics there is the math and the conceptual of what is happening.  Concept. How do you have an acceleration of 0 m/s/s.?

Sent from my iPhone

On Apr 10, 2011, at 5:54 PM, Orrin B Iseminger <obise at moscow.com> wrote:

> -----Original Message-----
> From: sel-bounces at lists.stationary-engine.com
> [mailto:sel-bounces at lists.stationary-engine.com] On Behalf Of Rob Skinner
> Sent: Friday, April 08, 2011 6:38 AM
> To: The SEL email discussion list
> Subject: Re: [SEL] OT: Physics Help
> 
> 
> 
> On Apr 7, 2011, at 8:49 AM, Orrin B Iseminger wrote:
> 
> 
> 
>> You can do it, too, Devin.  The most important thing for you to
> 
>> remember is to plug not only numbers into your equations; but, words as
> 
>> well.  If you do that, problems solve themselves.  For instance:
> 
> 
> 
> Orrin, are you sure you're not teaching Devin about Chemistry, and not
> Physics? The reason I ask is that concept is what I took with me after being
> paroled from Miss Holey's high school chemistry class. The lady was so mean,
> that rather than kick insubordinate teenagers out of her class, she would
> keep us there and cruelly inflict Chemistry upon us. 
> 
> 
> 
> Upon me, she caused permanent scarring. To this day, I still suffer a
> variant of Stockholm Syndrome, where I am obsessive about adding labels to
> every item in an equation. While figuring out anything complex enough to
> require pencil and paper, I compulsively add labels. If someone comes to me
> with a problem that is not properly labeled, I do not even want to talk to
> them until they properly construct the equation. 
> 
> 
> 
> Devin, even if the math is simple, add the labels. Your equations will be
> self-checking. If your labels end up all screwy, you know that you goofed it
> up. If your labels end up just as you expect, it's an indication that you've
> done a good job.
> 
> 
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> 
> 
> Rob, you blew my cover.  :-)  Actually, I *did* learn the importance of
> labels (units) in college freshman chemistry class.  It was this way:
> 
> 
> 
> Our freshman chemistry class was lucky enough to have Doc Willard teach us.
> He was the best and we students were smart enough to know we had a gem for
> an instructor. When he sidetracked onto his involvement in the Manhattan
> Project he kept all of us sitting on the edge of our seats.
> 
> 
> 
> Unfortunately, the dolts in charge of our laboratory sessions--more brain
> dead graduate student TAs--couldn't explain the difference between a mole
> and a graduated cylinder.  They were the ones who were supposed to be
> teaching us how to work the problems.  None of us caught on, except for one
> fellow, Jim Wilhelm, the class genius.  We were lucky enough to have him in
> our little circle of friends.
> 
> 
> 
> Just like everybody else in the class (except Jim), when it came to test
> time, I flunked all the problem-solving questions.  To keep the whole class
> from flunking, Doc Willard was forced to grade on the curve.  
> 
> 
> 
> I was still completely in the dark until the night before the final exam for
> the year.  Our little clique got together in the basement of a frat house in
> order to cram for finals.  One little question of mine revealed to Jim what
> I didn't understand.  In about two sentences he showed me the big picture; I
> saw the light.  It is something the graduate students couldn't do in a whole
> year's-worth of four-hour labs.  
> 
> 
> 
>> From then, on, I knew how to deal with those very important labels (units of
> measure).  The next day Jim and I aced the final exam and in the process we
> blew Doc Willard's grading curve, sky-high.   He posted Jim's and my grades
> as A++++
> 
> 
> 
> End of story.  Now, I need to wipe the egg off my face.  In an earlier post
> I said:
> 
> 
> 
> Actually, it is much better to use fractional notation like this:
> 
> 
> 
>    32-feet
> 
>  -----------
> 
>      sec
> 
>     -----
> 
>      sec
> 
> 
> 
> And went on to say:
> 
> 
> 
> In the above example, remember how you divide fractions.  Invert and
> multiply.  Therefore, it is entirely correct to do the same in the above.
> Inverting and multiplying results in:  
> 
> 
> 
> 32-feet-second
> 
> --------------
> 
>     sec
> 
> 
> 
> That is wrong!  I failed to do what I said to do, invert and multiply.
> 
> 
> 
>   32-feet           32-feet           1          32-feet
> 
> --------------  =  -----------  X  ---------  = ------------ 
> 
>     sec               sec            sec        sec squared
> 
>    -----
> 
>     sec
> 
> 
> 
> Sorry about that, Devin.
> 
> 
> 
> Orrin
> 
> 
> 
> Orrin Iseminger
> 
> Colton, Washington, USA
> 
> http://users.moscow.com/oiseming/lc_ant_p/menu.htm
> 
> So many projects.  So little time.   
> 
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