I am on holiday today and trying to demonstrate to family and friends that engineers have social skills too, contrary to Dilbert’s view on the social skills of engineers, see http://dilbert.com/strips/comic/2013-11-19/
Winter in Okemos, Michigan.
When we lived in the USA, I remember seeing billboards along the Interstate with messages from FEMA telling us ‘Be Ready’, to prepare, to plan, and to stay informed. I was never quite sure what we were meant to be ready for since we lived in rural Michigan where we were fortunate not to experience violent weather and to be far from industrial plants that might explode and shower us with chemicals or radiation. The billboard advertised the FEMA website [www.ready.gov] which contains very little factual information about radiation but does imply you should seek shelter in the basement of tall buildings in the event of a nuclear accident. Some commentators have suggested that the psychological effects arising from fear of nuclear radiation can cause more health issues than the dosage received especially for those not in the immediate vicinity of an incident. So, knowing more about radiation in advance of an incident would be helpful and might also dispel many of the fears that cause opposition to nuclear energy.
So, does sheltering in a basement offer reasonable protection? Well, radiation is produced when radioactive materials decay and their atoms release protons and neutrons from their nucleus plus some of the electrons that orbit the nucleus. The protons and neutrons cluster together to form alpha particles (actually Helium nucleii) that are relatively massive and can stopped by a sheet of paper. The electrons, known as beta radiation, whizz out at high-speed but can be stopped by a thin sheet of Aluminium. High-energy photons are also released with the electrons and are known as Gamma radiation, which requires a sheet of lead or a considerable thickness of concrete to stop them.
So sheltering in the basement is a good idea especially if the building above contains a substantial amount of concrete.
Sources:
http://www.ready.gov/nuclear-power-plants
David Ropeik, Fear vs. radiation: The mismatch, in the International New York Times, Tuesday October 22, 2013. http://www.nytimes.com/2013/10/22/opinion/fear-vs-radiation-the-mismatch.html?_r=0
Not a decision to give up caffeine until the festive season but a remark by my Italian research student as he finished his cup of coffee on the flight back to England. He doesn’t consider what we serve in the UK to be coffee and he won’t be back in Italy until the Christmas vacation. We were in Italy visiting the laboratory with which we are collaborating on his research project. He is right, the coffee gets much better as you move south and east from the US and UK.
Next time you are enjoying a cup of coffee watch the swirls created as you or a friend stirs in some cream. You can see streak lines that show the path of the cream in the coffee and reveal the fluid flow in your cup. It is even better if you have a clear glass. You can use this as an Everyday Engineering Example to capture students’ attention and to illustrate the kinematics of fluids as in the 5E lesson plan below.
Last week I left the rubbish on the streets and encouraged you to make a mess in the classroom. Partly because kinematics does not help us to analyse the forces involved in sweeping rubbish or, more glamorously, an ice hockey puck. This is the realm of kinetics in which we need to consider the forces acting on objects to cause or impede their motion, such as the push from a broom and the friction against the pavement. See the 5E lesson plan attached for more details on how Newton’s laws of motion can be applied in these situations.
You might be thinking ‘why should engineers be interested in forces involved in sweeping rubbish?’ Well, it might not be as glamorous as designing sports equipment but someone has to design street sweeping machines that keep our towns and cities clean and it is arguably more beneficial to society and the environment. Of course, it would be better for the environment if we didn’t drop rubbish that needed sweeping but that’s another post…
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.
For a set of videos on kinetics try: http://www.khanacademy.org/science/physics/forces-newtons-laws
