Reel Physics: The Dark Knight - Truck Flip

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Flatfrog:
I enjoy this series a lot but I have to call you guys out about one bad habit that as a maths/science teacher I'm always having to explain to my students: inappropriately accurate values.

If you have chosen to estimate a number in your calculation, such as the 75km/h figure, you can't then turn that into a value in mi/h that's accurate to 6 significant figures. Similarly, you can't end up with a final answer that's quoted to the same degree of accuracy. The accuracy of your answer can never be higher than the accuracy of the numbers used in the calculation (and if those numbers themselves were estimates, you really should drop down by one significant figure). If you *do* use a pseudo-precise figure, it gives a misleading impression of the accuracy of the original measurement.

It's a bit like in news reports where they say something like 'The project cost $10m (6574663.27)'. Unless the project literally cost $10,000,000.00 to the cent, that value in pounds has got to be incorrect.

I really agree with this point. I get pulled up all the time for doing it in physics. It does give a misleading impression when you arrive at the final answer (KE = 2170.1kJ, PE = 462.952kJ) with such a degree of accuracy when in fact you've used estimates that are of a far lesser degree of accuracy.

Other than that, I'm really enjoying this show, and the addition of a CG (computer graphics, not centre of gravity) truck to model your maths was very helpful. And the bloopers are great, I always watch them. ;)

Keep it up! I'll probably be showing this video to some of my fellow maths degree students.

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