[FRIAM] Naïve physics question

Wed Feb 15 12:20:31 EST 2017

Frank, ‘n all. 

It looks like I am… not to put too fine a point on it… WRONG about this.  I hate when that happens.  It seems WILDLY counter intuitive to me, but so, I should admit, does most of physics.  

You are all going to have to explain it to me VERY patiently, perhaps over coffee, perhaps on Friday. 

Nick 

Nicholas S. Thompson

Emeritus Professor of Psychology and Biology

Clark University

 <http://home.earthlink.net/~nickthompson/naturaldesigns/> http://home.earthlink.net/~nickthompson/naturaldesigns/

From: Friam [mailto:friam-bounces at redfish.com] On Behalf Of Frank Wimberly
Sent: Wednesday, February 15, 2017 1:54 AM
To: The Friday Morning Applied Complexity Coffee Group <friam at redfish.com>
Subject: Re: [FRIAM] Naïve physics question

Nick,

Over the last 2 or 3 years I have replaced most of our incandescent light bulbs with equivalent (light output) LED bulbs.  Our electric bill has gone down about 20% summer and winter.

When I worked in the Robotics Institute I was leader of a project to put sensors all over a fluorescent lamp factory to increase yield.  That is, to reduce the number of defective bulbs (out of millions).  The Westinghouse engineers told us that certain large office buildings were optimized for minimum energy use for lighting and heat in a method that involved keeping the lights on all night.  This, however, caused a public relations problem in that people who saw them lit up complained about their wasting energy.

Frank

Frank Wimberly
Phone (505) 670-9918

On Feb 15, 2017 1:37 AM, "Nick Thompson" <nickthompson at earthlink.net <mailto:nickthompson at earthlink.net> > wrote:

All—

Can I piggy back on to Gary’s question with one of my own.  Much more naïve.  Even tho I am an ardent conservationist, I believe that claims for energy saving from light bulbs that don’t spill heat only approach truth in the warmest parts of our country.  Where yearly annual temperature average is less than human comfort, the cost from heat loss from incandescent bulbs is compensated by a diminishment in the cost of heating by other means.  This works particularly well with a reading lamp, which is warming you while it lights you.  Now in summer, the loss of heat from bulbs is actually a very bad thing because it has to be compensated for with airconditioning.  But summers in most of the country are way shorter than winters.  

I am sure I am going to get some sort of a lecture on the second law, here.  Spilled heat from inefficiently deployed light sources is STILL more expensive than heat directly extracted from gas or oil.  Not sure how to think about that. 

Nick

Nicholas S. Thompson

Emeritus Professor of Psychology and Biology

Clark University

 <http://home.earthlink.net/~nickthompson/naturaldesigns/> http://home.earthlink.net/~nickthompson/naturaldesigns/

From: Friam [mailto:friam-bounces at redfish.com <mailto:friam-bounces at redfish.com> ] On Behalf Of Robert J. Cordingley
Sent: Tuesday, February 14, 2017 11:11 PM
To: The Friday Morning Applied Complexity Coffee Group <friam at redfish.com <mailto:friam at redfish.com> >
Subject: Re: [FRIAM] Naïve physics question

Seems like from a thermodynamics question you can first think of having two identical systems with identical energy inputs. Unless one of the systems is capable of storing energy in some form differently from the other the equilibrium temperatures should be the same.

Now CFBs emit more of the their input energy as light which since the containers are transparent (presumably to the same light that's emitted, visible, UV, infrared) it will escape more easily. Incandescents generate a lot of heat for the same energy input which may not escape as easily as the light energy. It will depend on the thermal conductivity of the container's materials etc. If the CFB were 100% efficient all it's energy will leave immediately in a container that is 100 % transparent to its 'light' and show no temperature increase. If the incandescent's heat is transmitted as infrared energy at 100% efficiency along with any light then its temperature will show no increase either.  So the answer may have more to do with the properties of the containers than the properties of the lights. Practically, I'd expect A to warm up more than B because B's light energy will escape more easily with materials we are familiar with.

If both containers are opaque to all light (UV, visible and IR) and have the same thermal conductivity properties we are back to the first paragraph.

2c

Robert C

On 2/14/17 8:01 AM, Gary Schiltz wrote:

Since there are some non-naïve, i.e. professional physicists, as well as just gererally smart people in FRIAM, I pose the following fun question. Given: two transparent, sealed containers filled with air - one contains an incandescent light bulb A that consumes 100 watts of energy; the other container contains a fluorescent light bulb B that also *consumes* 100 watts of energy. Since B is of a more efficient design, it will produce more light than A. Assuming the same color temperature light is produced by A and B, and ignoring any feedback effects of rising temperatures inside the respective containers, will the temperatures inside the containers reach the same temperature? Naïve physicist G (me) thinks that since more light is escaping from the container containing B, that its temperature will rise less. G also thinks that if the containers are opaque, that the temperatures will rise by the same amount. But G is besieged with doubts. Please help G.

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