Mechanics is probably one of my favourite parts of the Mathematics A level course, so I welcomed the opportunity to deliver some Mechanics Professional Development when asked by teachers at Hailsham Community College. I think, for me, the thing about mechanics is that it deals with real-world scenarios that we take for granted every day, such as throwing a ball, driving a car, crossing a bridge etc.
We split the PD into two twilights making it easier for teachers to attend and to give a consolidation break between the first and second year’s content.
We did a few simple practical demonstrations, looked at the theory, and tried some practice questions. This acted as a catalyst for asking questions about why things didn’t happen as we expected.
We spent some time looking at the standard units for motion and considered reasonable values. For example, if I state in a question that Teresa runs at 10ms-1, or that the train’s average speed is 20ms-1, are those realistic values? You would probably think straight away that one of these must be wrong because a train will move more than twice as fast as Teresa! As it happens, Usain Bolt broke the world record in the 200m sprint in 2009 with an average running speed of 10.42 ms-1 So it is very unlikely that Teresa would be running at 10ms-1, probably 4 or 5ms-1 is more realistic. Similarly, 20ms-1 is about the same as 50mph, which could be a reasonable average speed for a train, especially when we consider that the train will be pulling into stations, so it would have a speed of 0ms-1 for parts of the journey.
We also talked about the modelling process and how its importance pervades the whole of mechanics. We must ensure our students understand terms such as “a particle” and that simplifying a scenario will influence the final solution. We looked at some real-life disasters that could have been avoided if a particular part of the modelling process had not been left out. For example, do you know about the Gimli landing in July 1983, or the Boston molasses disaster in January 1919, or more recently the collapse of part of the terminal at Charles De Gaulle Airport in Paris in May 2004? You can find out more about any of these and many more by googling “engineering disasters”. A little research in this area makes for a different type of homework task, can be fun to share and helps to reinforce the importance of modelling: getting calculations right, validation and being careful with units.
by Hazel Santineer’s