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It Just Is

James Shaw
I wonder how much of what we 'know' has ever been properly explained? Our teachers repeat what they have been taught and our text books are re-writes of earlier text books. Perhaps that is the way to pass exams, don't think about what is missing, just repeat what was taught and so it goes on.


Lately I have been looking through some of my old 'how it works' books from my childhood, encyclopedias, atlases and 'online' to see what they say about the Earth's seasons. At least they all agree! It is all down to the tilt of the Earth's axis, the northern hemisphere points towards the Sun in the summer and away from the Sun in winter. Simple! We don't need to know anything more.


A simple experiment: Take a dinner plate and place an apple near the rim with its stalk pointing slightly towards the centre, a model of the tilted Earth. Now slowly and carefully twist the plate on top of a table so as not to disturb the apple until the plate has turned through 180 degrees. Now which way is the apple pointing? Do you still understand the seasons or did you have a book/teacher that really explained it? Perhaps you are a heretic and thought for yourself? Andy Millar raised some of these issues in "You don't need practical skills to be an engineer", 'knowing' how to do something can stop new thinking.


Have a virtual mug of coffee and think about it!
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    Alasdair,

    I rather suspected you were looking at 'the problem' from 'the answer' backwards, whereas I was trying to work from what we seemed to being taught. Both approaches can work, but not at the same time!

    Motion of bodies is a subject that confuses many, (there is an Australian who makes a living by 'explaining' science yet when it comes to explaining motion it is quite clear he doesn't understand it, relying on stock answers which often don't fit the question!).

    My model, (I don't say it is right), puts all parts of a non-spinning body in circular orbits, an axis-maintained model has only the C of G in a circular path, everywhere else describes an ellipse. (Think of something like a 'No Entry' sign being moved in a circle on a flat surface. In one case the white bar is aligned with the centre of rotation, in the other the bar stays horizontal as the complete sign follows a circular path.

    Not quite related but I was playing with a couple of meshed gear wheels, (avoids slippage as when using coins), of the same size. I doubt if few people would immediately grasp what happens when one rotates around the other - even in front of their own eyes!).

    Regards,

    Jim
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  • 0
    Alasdair,

    I rather suspected you were looking at 'the problem' from 'the answer' backwards, whereas I was trying to work from what we seemed to being taught. Both approaches can work, but not at the same time!

    Motion of bodies is a subject that confuses many, (there is an Australian who makes a living by 'explaining' science yet when it comes to explaining motion it is quite clear he doesn't understand it, relying on stock answers which often don't fit the question!).

    My model, (I don't say it is right), puts all parts of a non-spinning body in circular orbits, an axis-maintained model has only the C of G in a circular path, everywhere else describes an ellipse. (Think of something like a 'No Entry' sign being moved in a circle on a flat surface. In one case the white bar is aligned with the centre of rotation, in the other the bar stays horizontal as the complete sign follows a circular path.

    Not quite related but I was playing with a couple of meshed gear wheels, (avoids slippage as when using coins), of the same size. I doubt if few people would immediately grasp what happens when one rotates around the other - even in front of their own eyes!).

    Regards,

    Jim
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