## The Magic Tool

Just quoting a recent Physics exercise:

*Question:** A man with a mass of 80 kg jumps horizontally from a wagon (on friction free horizontal rails) with a mass of 800 kg. At the liftoff, his speed relative to the wagon is 3 m/s. How much energy did the jump cost the man?*

**Answer:** E = 327.3 J

The other day, I broke my window pane and had to purchase a new glass. Hence I had to know the dimensions of my window. Unfortunately, I didn’t have an appropriate measuring tape and one has to know it very exactly when ordering glass. No problem: I expected the window to be almost quadratic and I guessed that the area would be about one and a half square meter. Now I pulled out my good old pocket calculator, hit `1.5`

+ `sqrt`

+ `enter`

and – surprise – got exactly 1.2247448713915890491 m as the side length. I think most scientific laboratories would – even using sophisticated equipment – have had serious troubles to meet that precision.

P.S. The inconvenient fact that the new pane did *not* fit, I can only explain by incredible malpractice of the manufacturer.