The tutor mentions a few points about diatoms. In my Feb 4 post I introduced protists, which constitute a kingdom of eukaryotic, mainly single-celled organisms. Protists are divided into plantlike and animal-like ones. Diatoms, from phylum Chrysophyta, are among the …

Biology: protists: diatoms Read more »

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The tutor shows the easy concept, from graph theory, of elementary subdivision. An elementary subdivision on a graph replaces one edge by two, with a new vertex installed between them. Consider the following two graphs: Graph 1 Graph 2 Graph …

Math & Comp Sci: Graph theory: what is an elementary subdivision? Read more »

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The tutor reviews the progress of thought about atoms through the ages. Democritus, a Greek philosopher living around 400 BC, is credited as the first promoter of the concept of the atom. He proposed that all matter consists of tiny, …

Physics: models of the atom Read more »

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The tutor gives an example with friction force. I’ve never been curling. Even so, I can imagine the following question resonates with many curlers and spectators: A curling stone is released at 1.2m/s. If the coefficient of friction between the …

Physics: friction force: how far will the curling stone glide? Read more »

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