Re: [Phys-L] [SPAM] Re: [SPAM] Re: The Make-Believe World of Real World Physics

["Anthony Lapinski" <Anthony_Lapinski@pds.org>]

I have plenty of incandescents for the rest of my teaching career. Very
useful tools. I also break a large one open and put in series with a small
one. Blow of the filament of the larger one to see what happens to the
brightness of the smaller one. Great activity ("Sensitive Filament") from
Square Wheels (Exploratorium Science Snackbook).

I have a Kia Soul, which also displays mpg. Very cool! Here's another nice
problem, which can be adapted to any highway:

While entering the Garden State Parkway, you take a ticket at one toll
plaza and exit at the next one a known distance away. The ticket is
stamped by a time clock as you take it at the entrance point. At the exit
point can the toll collector determine if you ever exceeded the speed
limit for the Parkway? Explain.

I get interesting answers on this one. It also leads to good discussions
about, you guessed it, average speed!


Phys-L@Phys-L.org writes:
> On 2013, Jul 30, , at 13:03, Paul Lulai <plulai@stanthony.k12.mn.us>
> wrote:
>
> > The 1wire 1 batteryb1 bulb lab is a great standard lab. It appears in
> many many programs (physics by inquiry, workshop physics, real time
> physics, modeling physics, hewitt, etc...) There is no trick. When done
> we make sure kids known the first time structure of a lamp, the need for
> a complete path in standard circuits, where there are conductors and
> insulators, that standard lamps do not have a preference for direction of
> flow, and more. Worth the time. Big payoff. Leads to many following
> concepts.
>
>
> I pray much of this transfers when incandescents (soon) are museum items.
> Well, disassembly of a domestically powered LED is instructive.
>
> Is it bad form to use hydraulic analogies? -- certainly less convenient!
>
>
>
> On 2013, Jul 30, , at 03:07, jbellina <inquirybellina@comcast.net> wrote:
>
> > I'm going to come out of left field with this, if you know what I mean.
> I think there are at least two good reasons for starting with average
> velocity problems.  
>
> > The first is that is all we really can experience in our lives. 
> Instantaneous quantities are mathematical idealizations, and not directly
> in our experience.  So if we want to begin concretely with our own
> experiences, there we are.  Thinking it this why leads to a natural set
> of developmental questions when we know the velocity is indeed changing. 
> Working with students to figure out how to do that gives a rationale for
> the development of kinematics.
>
>
> My Prius' display gives actuel MPG  (which is about as instantaneous as
> one may have w/o lab equipment) and a trip (averaged since the last time
> the reset switch pushed).   Does not a speedometer give "instantaneous"
> speed.  Average speed requires the collection of data and algebraic
> manipulation; unless ones GPS device does it.
>
> I'm often surprise that my calculation of average speed over a long trip
> (just traveled 3k mile in ~ one week) is about 60mph while during most of
> the trip I've risked a confrontation w/ the local hwy patrol.  Here's an
> appropriate calc. for students.  
>
> bc thinks he's French.
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