Great teamwork this week, with teachers, technicians and students all getting some great results using tracker.
We wanted to see if we could get some damping examples.
We took a pendulum that was just over a metre long and set it in motion over a blue tray. We filmed the pendulum and uploaded this into tracker. Part of a metre stick was used for calibration purposes.
Theo has analysed this to try to show that the amplitude remains constant, if there is no damping. The graph does seem to shift a little towards the positive direction and we are having some good ideas as to why, such as camera slide and swinging forward and back rather than side to side, but it was probably due to the blurred film.
We then poured water into the tray and repeated the experiment pulling the pendulum back to the same point. Angus produced the tracker trace below. This is pretty blurred and distorted due to the refraction by the water.
Daniel had a clearer film to analyse and got a great plot of displacement with time to show how the amplitude decays with time.
If you can afford the top of the range camera, unlike the teacher, you can get a lovely plot, even if the pendulum appears to be hanging upside down!
You can clearly see that the amplitude decreases. Calculating the period, peaks arrive at the following times
We have always had a great deal of difficulty understanding the world view that quantum mechanics represents. At least I do, because I’m an old enough man that I haven’t got to the point that this stuff is obvious to me. Okay, I still get nervous with it…. You know how it always is, every new idea, it takes a generation or two until it becomes obvious that there’s no real problem. I cannot define the real problem, therefore I suspect there’s no real problem, but I’m not sure there’s no real problem.
Richard Feynman, in Simulating Physics with Computers appearing in International Journal of Theoretical Physics (1982) p. 471.
We choose to examine a phenomenon [Double-slit experiment] which is impossible, absolutely impossible, to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery. We cannot make the mystery go away by “explaining” how it works. We will just tell you how it works. In telling you how it works we will have told you about the basic peculiarities of all quantum mechanics.
Richard Feynman,The Feynman Lectures on Physics: Commemorative Issue, Vol. 3 Quantum Mechanics (1989) 1-1, “Quantum Behavior.”