Re: [Phys-l] three central misconceptions about relativity

["Craft, Peter" <PETER.CRAFT@det.nsw.edu.au>]

Thanks to everyone for their input. Unfortunately I did not make my question clear, so I will try and clarify what it is I want to know.

Firstly, I put the sample questions at the bottom of my post simply to illustrate the sort of questions the students are assessed on. Answering those questions posed no particular problems for me (nor I hope for them). In fact they are not particularly "testing" questions, if you will forgive the pun.

The exert from the Syllabus is more important to me, in that the Syllabus document represents the material that I am supposed to impart to students. When I teach Phyiscs I want to:

a) Improve students' understanding about physics and the universe they live in
b) use good pedagogy that helps develop their conceptual understanding, improve their scientific skills and fuel their curiosity; so that they have a love of thinking about and learning about our universe
c) prepare students who are going on to further study.

I am particularly concerned that what they learn in my classroom will not have to unlearned or undone in university. I would hate to be teaching my students misconceptions and harming their learning. 

SO, given the material the syllabus says I am supposed to cover and given the statement by JD - 

> > 3. explain qualitatively and quantitatively the consequence of
> > special relativity in relation to:
> >
> > – the relativity of simultaneity  – the equivalence between mass and
> > energy  – length contraction  – time dilation – mass dilation
> Jeepers!  
> a) Relativity does in fact explain the breakdown of simultaneity 
  >at a distance.  However ...
> b) The idea of clocks that can't be trusted is a Bad Idea
> c) The idea of rulers that can't be trusted is a Bad Idea
> d) Mass is provably not equivalent to energy.  I assume you realize
  >that if you go down that road, you wind up with a longitudinal mass
  >and a transverse mass and who-knows-what-all else ... and they can't
  >all be equivalent to the energy.
> e) More generally, the idea of velocity-dependent mass is a Bad Idea.
> Ideas (b) through (e) are as dead as phlogiston.

What approach should I take with my students that will allow me to cover the Syllabus (in case they are asked inane questions about length contraction etc) but wont harm their learning about relativity at an intro level?  For example, should it be a historical approach that leads to a modern understanding OR some other approach that then looks back at the Syllabus and critically evaluates the content we are asked to teach? I would appreciate some thoughts on this.

Regards

Peter Craft
Head Teacher Science
Corowa High School

Phone 02 6033 1889
Fax 02 6033 1889
________________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Craft, Peter [PETER.CRAFT@det.nsw.edu.au]
Sent: Monday, 17 October 2011 11:44 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] three central misconceptions about relativity

Gday All,

John Denker earlier stated <Again:  Just because Einstein used contracted rulers and dilated
clocks in 1905 doesn't mean it is a good idea.  In fact it is a terrible idea.  It is *incompatible* with a modern (post-1908) understanding of the subject.>

In our state mandated Physics Syllabus, the document we base our teaching on and on which our state wide assessment material is based it says (in part)

 1. identify that if c is constant then space and time become relative

 2. discuss the concept that length standards are defined in terms of time in contrast to the original metre standard

 3. explain qualitatively and quantitatively the consequence of special relativity in relation to:

  – the relativity of simultaneity  – the equivalence between mass and energy  – length contraction  – time dilation – mass dilation



Remembering that student are going to be asked question directly on this material, what is the *best* approach for giving my students a good intro level understanding of relativity while at the same time enabling them to answer questions in the state test?



They are asked questions such as



a) How has our understanding of time been influenced by the discovery of the constancy of the speed of light?

b) piece of radioactive material of mass 2.5 kilogram undergoes radioactive decay. How much energy is released if 10 grams of this mass are converted to energy during the decay process?

c) A mass is moving in an inertial frame of reference at a velocity v relative to a stationary observer. The observer measures an apparent mass increase of 0.37%.Calculate the value of v in m/s.


Regards

Peter Craft
Head Teacher Science
Corowa High School

Phone 02 6033 1889
Fax 02 6033 1889
________________________________________
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