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As the responses to this HN post demonstrate so clearly, an intuitive understand of what Archimedes Principle means in the real world is not something that is e
by pja 13y ago
As the responses to this HN post demonstrate so clearly, an intuitive understand of what Archimedes Principle means in the real world is not something that is easy to acquire: I'm sure most of the commentators on this HN post are intelligent people who probably did well at school, yet the majority of the responses here are completely wrongheaded.
If it isn't transparently obvious that the water level will neither rise nor fall but stay exactly the same then you don't really understand Archimedes Principle.
The author's question therefore is: how is the Khan academy approach supposed to improve on this situation? A bare explanation of Archimedes Principle clearly isn't enough, nor is the ability to parrot said explanation after viewing the explanation it as many times as required for the viewer to learn the required words. How then is a learner going to acquire authentic understanding from Khan academy videos?
(Note that traditional education has clearly failed here too! But that's a side issue: the question here is why should we expect Khan academy to do any better?)
- himangshuj 13y agocan't agree more. I have been studying education sector in India, home to largest number of potential beneficiaries of khan academy. I would say khan academy is already bettering normal education. most teachers here would have no clue of archimedis principle atleast khan academy is giving the right information whether all the students are able to absorb is another matter
- jcampbell1 13y ago> If it isn't transparently obvious that the water level will neither rise nor fall but stay exactly the same then you don't really understand Archimedes Principle. Surely it will overflow once the ice melts. At about 4C the water will reach it's lowest point, and then rise and start overflowing at about 8C.
- pja 13y agoThe density change in the liquid water due to heating / cooling over the likely temperature range is tiny compared to the result of going from ice to liquid water. But I'll award you pedantry points nonetheless :) The precise outcome requires knowing the volumes and shapes of the ice and water components, their initial temperatures and the temperature of the ambient environment so that you can calculate the path of the water volume over time as the ice has melts. In order to make that calculation you'd still have to make use of Archimedes Principle in order to know that you didn't need to worry about how much water was displaced by the floating ice in your calculations, which was the original point.