Dot Physics

This is great. Many people have already reported google’s apple-dropping homepage in honor Newton’s birthday. In case it disappears, here is a screen shot.


So, I got this awesome note from Dale Basler. He said that his class had analyzed this falling apple animation. What a very Dot Physics-y idea (check out his analysis). He said they were questioning the results which might be due screen capture issues. I decided to reproduce this.

I captured the motion with Apple’s Quicktime X screen recording feature. I then used Tracker Video Analysis – which now has an autotracking feature that works really well in this case (I will post more about that later). Here is a plot of the y-motion of the falling apple.


I fit a parabolic function to the data (at least to the part where it was falling) and I get an acceleration of about -2 units/sec2. I didn’t scale the video so I don’t really know the distance units. Is it constant acceleration? Kind of, I guess. What about the bounce? That should have the same acceleration, right?


Not even close. I guess google thought it would be enough to honor Newton with the silly falling apple, but not falling with a constant acceleration. Hello, Google? I thought your motto was “do no evil.”

Actually, this doesn’t bother me too much – but I thought the analysis was a cool idea.


  1. #1 David
    January 5, 2010

    Can’t you scale the drawing by the size of the apple? (Yeah, I know, I know – apples aren’t a set size – but they fall within a certain range – and that gets you a range that may or may not include the g we’re expecting).
    And no, we don’t know what planet this is on – but it’s one that has trees more or less like ours, so g can’t be too different (unlike Pandorum…)

  2. #2 Samuel Martins
    January 10, 2010

    Maybe it was windy…

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