# Practical mechanics: how much power does Thomas the Tank Engine have?

Tuesday 12th January 2021

Back in March 2020, we were due to run a professional development day on some of the mechanics topics from Further Mathematics. Practicals aplenty were planned, with topics including impulse and restitution, energy and power, and the simple harmonic motion work that is in the pure side of the Further Mathematics course, but is really mechanics!

You won’t be surprised to read that the course had to be cancelled and, at the time, I emailed the teachers who were due to attend to say that we hoped to run it in the autumn term. September came and went, and we were no closer to running the event, but these teachers needed a fix of mechanics, so it was time to plan an online alternative – but how do you take a day built around practical experiments and do it online?!

I happened to be teaching some of these topics in October to my own Further Mathematics class and suddenly a solution became clear – I’d perform the experiments myself, film them, and upload the videos to Desmos, so that during the session teachers could watch them, get any measurements they needed, and calculate values and make predictions. Whilst filming the experiments, I also learned something. Usually when doing a practical, any timing is usually a large source of error – I often have four or five students timing with a stop watch and we take some sort of average (the arithmetic mean typically!) of their wildly varying results. However, with a video you can click through the frames and note the times, meaning times to the nearest tenth of a second are now reliable – or even to the nearest hundredth of a second!

The teachers who were due to attend in March were invited to the online sessions (one on collisions and one on work, energy and power – delivered two weeks apart), and the virtual practicals went down well. We calculated an estimate for the power of Thomas the Tank Engine (well, my son’s toy one!) and the coefficient of restitution for marbles and bouncy balls. It wasn’t all playing with children’s toys though – we looked at how some of the formulae can be derived and finished with discussion of examiner advice.

Whilst I would have much preferred to have done this course in person, with the teachers able to chat face-to-face and do the practicals themselves, the technology we have available to us now means it’s possible to have a session on practical experiments completely online! I’ll finish with a few quotes from those who attended:

• I liked the videos to make it more practical and see the actual use
• I loved the real life Thomas example

Thanks need to go to Ted Graham and Ben Sparks for their contributions – for a combination of supporting sessions, giving me ideas and generally being inspirational.

By Pat Cobb