Sunday, January 13, 2013

Ball in gravity and air drag

My sister in law is an intelligent fine young woman, and a high school teacher, living in France.

Over the last 2 years,  traditional education in the US has been seriously shaken by the sudden and massive popularity of online courses, as the coming of age of web technologies has made them possible for teachers and pleasant for students.

The breakthrough came from Salman Khan who founded the now famous (and fantastically useful ! - not just to students) Khan Academy. The first unsolicited feedback he got from his youtube viewers say a lot about the depth of the demand for good quality education/instruction. In hindsight, it need not be that big a surprise, as the irrepressible urge to know/learn/discover is quintessentially human, particularly among young people. After all wikipedia, another spectacular success driven by people's appetite for knowledge, had already surpassed centuries old institutions like the Encyclopedia Britannica. And his extraordinary success, signalled by a Forbes' cover page, is all the more noticeable than his endeavor is not-for-profit.

At university level, the first foray into MOOC (massively open online courses) came from, I believe, Stanford's professors Sebastian Thrun and Peter Norvig with they Artificial Intelligence class in the last quarter of 2011. Surprised by the number of applicants (more than 50,000 !), and impressed by the potential impact, they founded Udacity. Many universities have quickly followed suit and soon after founded Coursera, which aggregates online courses from many universities, and edX, created by Harvard and Berkeley. Everybody clearly feels the trend and jockeys hard to capture audiences.

There many reasons why students like these courses: Each person can go at their own pace, rewind as many times as they like (or fast forward say x1.5 if they find it easy - I love this feature in Coursera), do the exercise as the same time as the teacher, choose the time of viewing (when they are more alert), pause and browse other relevant content in case of a digression. And it is virtually free. In the US where tuiton fees have skyrocketed over the last decade, while the value of a degree on the job market has not risen (maybe Ivy league universities excepted), this is bound to become a compelling argument.

The teachers (at least the good ones) love it too. All of a sudden, their personal impact can grow beyond any proportion envisaged in the previous paradigm. They used to be theater actors, playing to a a local audience only. Now if they are successful they can become movie stars, international celebrities! The consequence is not only on their egos. The best courses become famous and available to every student, not only in space, i.e. nationwide and across borders, but also in time. And I don't mean only late at night for working people who do evening classes, but in the long run. Many subjects are stable and taught in exactly the same way years after years. The properties of the golden number are eternal.

An immediate consequence is increased competition among teachers, internet style rankings of courses/teachers, as in Coursetalk for example. Competition being stimulating, it is probably interesting to be a teacher these days as the range of tools has expanded beyond the previous generation could imagine, and the potential impact mind blowing - but the mission has lost none of its fundamental nobleness.

For now the vast majority of the online revolution is taking place in the US, as always in all things digital. They have not only invented the internet, they have continuously perfected it and keep on applying its immense potential to new fields. In long History, I am persuaded that centuries from now some scholars will reflect on the impact of late 20th / early 21th century US/California and marvel at the dynamics that led to all this creative bubble and ponder its far reaching consequences. In the same league as fifth century Athens ?..

So, I was saying that my sister in law is a high school teacher, specialised in physics/chemistry, in France, where hardly anything mentioned above has been seen. One valid reason is that, by and large, education is free - because heavily subsidised by the state.

But as I tried to outline (ok, it is obvious) the trend is unstoppable and will soon cross the Atlantic. It is always good to be warned that a tsunami is coming. So I am gently pushing her (I should say delicately suggest, or subtly entice, or even flatly inform, but I should certainly never say push !?!!)  to dive in and embrace the revolution, for the benefit of her students, and hers.

With this in mind, I set about to design a simple program that computes and displays the motion of a ball subject to gravity and air drag. I wanted the code to be visible so that a student can change the initial position/speed of the ball, its radius, mass, and bounciness, and immediately see the result. The two in-browser environnement that I have spotted are and Finally because it seems a little more polyvalent ( is designed with d3.js, another excellent visualisation javascript library), I went for but I loved the 'click-and-drag' of any variable and the instant visualisation of the result in

Here is the jsfiddle to play with.

And below is the result, written in processing (even though the tab says javascript), as the code is more intuitive, so probably easier to read and tamper with than pure javascript.