Tag Archives: Back of the Envelope

Why is Multiplication Harder than Addition?

I’m in the process of writing a couple of blog posts about slide rules, and an interesting questions occurred to me, which spawned this post. Why is addition so much easier than multiplication? The power of slide rules comes from … Continue reading

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Work Done By The Human Heart

I was reading a book on thermodynamics and for some reason they threw in the fact that each beat of a human heart is about 1 joule. Of course I did what any self-respecting scientist does, I reached for the … Continue reading

Posted in Learning Physics | Tagged | 9 Comments

How High Can Mountains Be?

Last month Rhett Allain posted about the famous Bent Pyramid in Egypt. As part of his calculations he estimated how high a stack of stone blocks can be without collapsing. The value he came up with was 3200 m, which … Continue reading

Posted in Learning Physics | Tagged | 9 Comments

In Defense of Dot.Physics

A recent post by Rhett Allain of Dot.Physics fame has drawn a number of negative comments and I wanted to address the concerns that came up. The post is titled Does the Slope of a Pyramid Really Matter?¬† and the … Continue reading

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Photosynthesizing Felines – A Back of the Envelope Calculation

The other day I was out weeding in the garden, amazed at the ability of weeds to take over all the tasty plants. ¬†Just think of all the energy that must go into growing these weeds, just to be heartless … Continue reading

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