Category Archives: Learning & Teaching

Flexible credit

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vibrating rulerOne of the major credit card companies used to advertise their card as ‘your flexible friend’.  If you clamp your card over the edge of the table and flip it with your finger then it will vibrate at a resonant frequency which decreases with length of the overhang, or cantilever as engineers might call it.  You could say that your flexible friend can sing too.

I used to use a twelve-inch ruler as everyday example of free and forced vibrations until someone pointed out to me that most engineering students don’t carry them around any longer.  So the credit card is a nice alternative that everyone carries with them, although the embossed text of your name and account number makes them a little too stiff and you might find that your plastic driving licence works better.  Neither will produce middle C as well as a plastic twelve-inch ruler – you can calculate the resonant or natural frequency by equating the kinetic energy and strain energy of the cantilever, as illustrated in the attached 5E lesson plan.  For more on 5E lesson plans see: my post entitled ‘Disease of the modern age’ on June 26th, 2013 and ‘Sizzling Sausages’ on July 3rd, 2013.  By the way, kinetic energy is the energy possessed by an object due to its motion and strain energy is the energy stored in an object as result of elastic (reversible) deformation and is equal to the work done in producing the deformation.

5EplanNoD12_free&forcedvibrations

Chemical Imbalance

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chemicalimbalance

Cover of the book to go with the film

 

 

 

 

 

 

 

 

 

 

A couple of weeks ago I blogged about population and its rapid rise (see ‘Population Control’ on September 25th, 2013).  Despite our burgeoning population many university engineering schools in the English-speaking world tend to recruit from only half the population, i.e. the male population.  Representation of females in engineering is woefully low, generally worse than in science.  To learn more how women feel about the situation in chemistry watch a short film called ‘A Chemical Imbalance’  – I highly recommend that you spare the 15 minutes to watch it at  http://chemicalimbalance.co.uk/

Go on do it now! The rest of this posting is boring stuff so watch the film which was made with support from the Royal Society.

In the film ‘the leaky pipeline’ is talked about in the context of women entering science and engineering not making it to the top.  Of course this is not unique to science and engineering; only about 20 of the Fortune 500 companies have a female CEO.  This is an important issue but the supply to the pipeline is a bigger problem.  Only 20% of the students awarded an A-level in Physics in the UK this year (equivalent to AP exams in the US) were female and since most university engineering programmes require Physics the supply of qualified women is almost decimated before it gets to the pipeline.  This year my school has taken the step of dropping the physics requirement and accepting that we will need to teach the necessary physics as part of our engineering courses; incidently we also raised the grades we require so this does not represent a lowering of standards!

Another sobering thought is that nearly half of co-education state schools in the UK had no females studying for A-level physics.  I don’t have statistics for the US but I suspect they would be the same.

Anne-Marie Slaughter, a political scientist at Princeton argues that ‘the way we view women [has] changed radically, [but] the way we view men not at all’ so that achieving further gender equality requires a cultural change about and by men, which is going to be tough in a male-dominated conservative profession like engineering but we have to do it.  So if you didn’t watch the film, do it now and think about how you can be an agent for change.

Sources:

http://www.bbc.co.uk/news/education-19603399

Eduardo Porter’s column ‘Economic Scene’ entitled ‘Is leaning in enough to fix the gender gap? in the New York Times on September 24th, 2013 see http://www.nytimes.com/2013/09/25/business/economy/for-american-women-is-it-enough-to-lean-in.html?ref=eduardoporter&_r=0

Stonemasons and skateboards

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skateboardWalking through campus last week I saw a stonemason carving small chamfers every 30cm or so around the edge of plinth being prepared to receive a new sculpture.  A few days later there were metal tabs fitted in the chamfers, presumably to discourage skateboarders from using the plinth for acrobatics.  These metal tabs are becoming as common in our public places as the skateboarders they are designed to discourage.  I can understand old people being worried by fast moving youngsters on skateboards, but the speed and freedom of movement is part of the attraction for young people.  As a teacher of engineering, I see the skateboard as another everyday example of engineering with which to liven up the classroom and grab students’ attention.  Try riding a board into class to engage attention!

Below is a ‘5E’ lesson plan for beam bending theory based around a skateboard.  For more on Everyday Examples in Engineering ‘Bridging Cultures’ on June 12th, 2013; and ‘Disease of a Modern Age’ on June 26th, 2013.

5EplanNoS8_beambending&skateboarder

Teaching stress

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ipodDuring my trip to the US (see post entitled ‘Detroit’, on 21st August, 2013), my earphones for my IPod broke.  This seems to be a common occurrence, perhaps a case of the planned obsolescence I wrote about on May 1st, 2013 under the heading ‘Old is Beautiful’.  Nothing very beautiful or repairable about broken earphones, they are just part of our disposable culture.  However, I collect them and use them when teaching engineering students about stress and strain.  Students have all experienced such a failure and so it is an everyday example of engineering that can be used to teach the principles of stress and strain in a familiar context.  A suggested 5E lesson plan for doing this is provided at the bottom of this post.

The lesson plan deals with the stresses in the earphone cable when the ipod is dangled from them and the discussion in class can be extended to include the stresses induced by spinning the earbuds on the end of the cable or the effect of repeated bending of the cable leading to possible fatigue failure (like when you bend your old credit card back and forth to snap it in half).

For more on Everyday Examples in Engineering ‘Bridging Cultures’ on June 12th, 2013; and ‘Disease of a Modern Age’ on June 26th, 2013.

5EplanNoS1_uniaxialstrain&ipod