'Efficiency through simplicity'

I stumbled across this website that features a home which claims to have the best Home Energy Rating System (HERS) value in the country.

http://www.electronichouse.com/article/power_house_of_energy_efficiency/

This home in Sarasota Florida has a roof that is covered with solar panels and no less than 7 flat panel HDTV's, 6 inside and 1 outside.  The article touts this home as an example of 'efficiency through simplicity'.  I am surprised that the author doesn't see the irony in associating a huge house with 7 TV's with the simple life.  Don't worry about the evaporative water loss from those huge pools with built in fountains either.  According to the article the house also 'saves water'.  The rain is collected on the roof and is used in the horse stables.  If only the 7 billion residents of our planet could all live this 'simply' ;-)

Energetics of healing wounds

David Fortus sent this review of a recent article on the energetics of wound healing. 

http://www.technologyreview.com/view/509071/energy-conservation-and-the-puzzle-of-the-bodys-healing-rate/

I am amazed that energetics might be a limiting factor on the rate at which our bodies heal. 

Apell and co calculate that growing new cells requires, on average, about 20 kiloJoules per gram of new tissue grown. “This means in physical terms that wounds acts like substantial energy sinks,” they say.

Certainly only a small percentage of this 20kJ/gr is actually stored as chemical energy in the new tissue so wounds are not just acting like energy sinks.  I wonder if you can actually detect a healing wound thermally by the rise in temperature in the vicinity of the new tissue formation. 

Causing an object to roll vs. giving it energy

In the presentation by Sara Lacy at the Energy Summit I really liked the subtle distinction Sara described associated with the energy story of a person (Jim) rolling a ball.  We might assume that if learners understand that, Jim has energy, the ball gets energy, and Jim caused the ball then it would be obvious to them that Jim gave the ball some of his energy.  Sara suggested that this last point is not an obvious leap for 3rd grade learners.  When a marble strikes a stationary marble, it is may be clear that the motion energy of the first marble decreases.  When a person rolls a ball it is not nearly as clear that the energy of the person decreases in the process.  As we develop energy learning progressions for young learners it will be necessary to really listen to them so that we can understand some of the unanticipated places where they will experience cognitive challenges.

Intuitive perceptions of relative energy quantities and a doughnut hole

We have recognized for quite a while that some learners intuitively underestimate the amount of thermal energy involved in some scenarios (ex. block sliding to a stop).  For some reason the amount of thermal energy increase in the floor and block does not seem adequate to account for the decrease in kinetic energy.  I recently was introduced to another discrepant energy event which might suggest that in some scenarios learners underestimate chemical energy relative to thermal/light energy.

http://www.youtube.com/watch?v=c2CFSrazKTg

(skip to 1:20 if you want)

In stark contrast to the sliding block scenario, here there seems to be much more thermal energy than is reasonable to account for the chemical energy in the donut hole.  I wonder if this is related the Brain Rules concept that our brains have evolved to attend to potential threats.  The sliding block could hurt me but the warm floor could not.  The flaming donut hole could hurt me but the chemical energy in the donut hole could not.

Metaphor and degradation in China

One of the pleasures of attending a meeting that is intentionally international is the opportunity to have personal connections with scholars from all over the world.  I was surprised at the Energy Summit to hear from a scholar from mainland China who is trying to apply ideas from Lakoff and Johnson to entropy and Gibbs free energy.

http://esummit-msu.net/content/several-often-neglected-perspectives-energy-chemical-education

This paper is quite long and will need serious shortening and editing if it is to be included in the ES book. I have not had time to read it yet. Nevertheless, the paper represents some very careful and creative thinking about energy/entropy concepts.  Wei makes the argument that, contrary to common thinking, there is no tendency to minimize energy.  The Gibbs free energy should not be thought of as a competition between minimizing energy and maximizing entropy.  Instead minimizing Gibbs free energy is just a version of maximizing entropy in a constant pressure and temperature environment.  Gibbs free energy is simply a quantity which is measured in energy units and which decreases (for a system in a quasi constant pressure and temperature environment) whenever entropy increases (overall).  This framing would suggest that the Gibbs free energy may have a very close relationship with the idea of energy spreading in a quasi constant P, T environment.  I will have to think much more about this.

When does a mousetrap have zero elastic energy?

Stamatis and I gave a final question involving the energetics of a mouse trap car. A student came up during the exam and asked, 'should we assume that the mousetrap has zero elastic energy when it is fully sprung?' I was impressed by the insight of this student and the fact that neither Stamatis or I had reflected on this point in writing and reviewing the question. In fact, the Physics Teacher article that we quoted in the question says 'just as the arm arrives at its most forward position, when all of the spring potential energy has been expended...' But as this student clearly recognized the spring of a fully sprung mousetrap still has elastic energy to give.

Thank goodness for student insight and for Stamatis who will be grading this question.

Research on Hidden Thermal Energy Scenarios

Amy and I met today to talk about a paper we will be writing together. We discussed several possibilities but settled on a paper focusing on hidden energy scenarios.