Relearning Physics

I remember the clarity and rigour with which I used to explore (theoretical) Physics, when I was in the Eleventh and Twelfth standards, thanks to the inspirational teaching of Gopinathan sir. But after that, I have really been struggling to make sense of what I am learning at college. Working here under Ajith sir, has been a breath of fresh air.

Documenting the experiments properly, has proved to be a challenging job, because you have to verify everything once again before making the report. I don’t know how much I’d be able to complete, but it’s been a good experience.

There is an experiment which you usually do at school, in which you measure the time period so as to calculate the value of acceleration due to gravity from it. But the whole equation is valid for only small amplitudes of oscillation, because the sin(theta)=theta approximation is used. For large amplitudes, this equation is to be used. It must have been mentioned back then, but it sure didn’t stick. There’s no way you can actually verify that in a school lab.

But with Phoenix, you can! We experimented with a combination pendulum, which is nothing but a metal ball fixed on a thin metal rod. It’s similar to the simple pendulum, except that it has a rigid rod, which makes it stable, and that you have to consider the moments of inertia of the rod and the ball. A very thin needle (whose effect can be neglected) was attached to the pendulum, to measure the approximate value of amplitude, as shown in the picture.

We got beautiful results from this setup, and could fit the data onto the large amplitude equation almost perfectly. Measuring the amplitude was the tricky part. Time period can be measured with microsecond accuracy using Phoenix. For each value of amplitude, ten readings were noted. On extrapolating the graph, you can get the time period as the amplitude tends to zero. It was a fascinating result, because you never really carry out experiments from such angles, in our schools/colleges. Hopefully Phoenix can change that!

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