Author Archives: Eann Patterson

Singing in the rain

Followers of this blog might have deduced that I live within sight of the sea, which means that it is nearly always windy.  After a rain storm the streets of the city are usually littered with broken umbrellas.  I suspect that most of these belong to the many tourists that visit Liverpool, because local residents know that the wind will wreck any umbrella that you are brave enough or foolish enough to put up.

It is relatively straightforward to estimate the forces involved in holding an umbrella up in a gale by using control volume analysis.  The lesson plan below includes this Everyday Engineering Example together with two more control volume analyses.

Momentum 5EplanNoF5_momentum

The title of the posting is pretty tenuous this week: Gene Kelly sings ‘Singin’ in the rain’ without an umbrella in the film of the same name, see www.youtube.com/watch?v=D1ZYhVpdXbQ – well its difficult to be creative all of the time, or even some of the time!

See also the Everyday Engineering Examples page on this blog for more lesson plans and more background on Everyday Engineering Examples.

What is Engineering?

Engineering turnover in the UK was £1.1 trillion (for the year ending March 2012) which was 24.5% of UK turnover.  So clearly engineering is big and important to the economy of industrialised countries.  But what it is?  That’s a harder question to answer!  In 2013 almost two-thirds of the public could cite the engineering development of the last 50 years that has had the greatest impact on them – that compares with slightly more than one-third in 2010 so more people are beginning to recognise engineering when they see it.  Can you cite the engineering development that has had the greatest impact on you?  If so, post a comment (use the ‘Leave a reply’ box at the bottom of the page).

What is Engineering? As well as being the title of this post it is also a website that attempts to answer the question. You will find the classical answers there and elsewhere, i.e. that engineering is about taking the resources able in nature and converting them into products (e.g. buildings, computers, medical devices and planes) and services (e.g. water, electricity and communications) for society.  Engineers are problem-solvers who communicate and organise the implementation of solution which might be how to create a zero emission car or a carbon-neutral public building.  The best engineers look for elegant solutions so I rather like the no.2 definition that you get when you Google the question, i.e. ‘the action of working artfully to bring something about’.

Source: www.engineeringUK.com

Gadget stress

2d543f31-6f09-43ba-875c-c2d5d3bd0cebWe went to the last night of ‘Twelfth Night’ on Saturday at the new, or rather completely rebuilt, Everyman Theatre in Liverpool. It was tremendous entertainment with songs and dance, Shakespearean comedy with a Scouse accent and an exciting start with Viola and the captain of the wrecked ship surging, dripping wet, onto the stage from what looked like a broken mirror lying on the floor but turned out to be a pool of water. Especially exciting for those sitting in the front row, since the Everyman is a theatre in the round and the front row probably got wet! They certainly had stage hands mopping up around their feet at the end of the scene.

I was amazed at the interval to see people on their smart phones and tablets. Maybe they were communicating their excitement about the production on social media but perhaps more likely they were desperate to find out what had been going on in the world and who had sent them messages. For me, time ‘off the grid’, disconnected from the electronic world is precious and to be protected but many people find it hard to disconnect and appear addicted. Our gadgets pander to our tendencies to be workaholics and to socialize.

Dr R. Thara, Director of the Schizophrenia Research Foundation in an interview reported in a piece by T.M. Luhrmann entitled ‘A great depression?’ in the NYT on March 25th, 2014 said “Gadgets. All these gadgets. Nobody thinks for themselves anymore.” We are certainly at risk of having no time to think for ourselves but the risk from our gadgets is more insidious because access to everyone else’s life via social media and professional networks can end up making our own life look dull and potentially depressing. Of course, most of us conspire in creating this false image by only telling the world about the good things that are happening in our lives.

It is better to pick up a good novel if we want to relax and find out more about ourselves. see my post entitled ‘Reading Offline’ on March 19th, 2014.

Reducing tension

bubbleHave you ever tried to float a paperclip in a bowl of water?  It is quite difficult but possible if you put the paperclip on a piece of tissue paper and carefully place the tissue paper with the paperclip onto the surface of the water; then, using a pencil slowly push the tissue underwater and, with a little bit of luck and practice, the paperclip will be left floating on the surface of the water.  The surface tension of the water counteracts the gravitational force on the paperclip.  This is the same mechanism that allows some insects to ‘skate’ across the surface of ponds.

Detergent is a surfactant which reduces the surface tension of the water.  So, if you drop a little bit into your bowl of water the paperclip will sink because the surface tension is no longer sufficient to support it.

This is not an experiment to demonstrate in class because it is too delicate and too small for students to see but students can do it for themselves at home.  An alternative for demonstrating surface tension effects is to blow bubbles using a detergent solution.  These two ‘Everyday Engineering Examples’ are described in the lesson plan below and you can watch a video clip about it at www.youtube.com/watch?v=BRyQvGEQUt0

5EplanNoF1_fluids&their_properties

See also the Everyday Engineering Examples page on this blog for more lesson plans and more background on Everyday Examples.