This week we’ve got the volume of a pizza, the reason Austria’s flag has a white stripe on it, and the explanation behind the phrase ‘Bob’s your uncle’. Oh – and the most fun you can have with an oven shelf without using it for cooking. Happy home schooling, everyone!
A pangram is a sentence that contains every letter of the alphabet.
The most famous example in English is: ‘The quick brown fox jumps over the lazy dog.’ People learning to touch-type often use this to practise their technique.
Another pangram is: ‘Pack my box with five dozen liquor jugs’. Or: ‘By Jove, my quick study of lexicography won a prize!’ (What does ‘lexicography’ mean? Why is it appropriate here?)
Can you work out a pangram of your own?
Imagine a pizza. Let’s say its radius is z, and its height is a.
The area of a circle is πr2. So the volume of a pizza is πr2 times its height.
Which means that the volume of our pizza is pizza.
(That’s pi times z times z times a. Mathematicians often write ‘ab’ instead of ‘a x b’. They’re lazy like the rest of us.)
The phrase ‘Bob’s your uncle’ derives from the occasion in 1887 when the prime minister the Marquess of Salisbury (Robert Gascoyne-Cecil) appointed his nephew Arthur Balfour as a Cabinet minister.
Strontian is the only place in Britain to have a chemical element named after it. The village on the west coast of Scotland lies in the shadow of some hills where a new element was discovered in 1790. Scientists named it strontium in the village’s honour.
In America it’s often the other way round – places are named after the elements found there. For instance there is Cobalt in Idaho, and Sulphur in Oklahoma.
Austria’s flag – red with a horizontal white stripe – commemorates Duke Leopold V, the country’s ruler from 1177 to 1194, who after a violent day on the battlefield took off his belt and revealed a clean section across his blood-spattered tunic.
Here’s a fun experiment to show how sound waves travel through solids. Take a metal shelf from your oven, and tie a piece of string about a foot long to one of its corners. Then tie another piece of string to another corner. Now wind the free ends of the strings around your index fingers (one string to each finger). Then put your fingers in your ears, and stand leaning forward slightly, so that the shelf dangles free in front of you, hanging from the pieces of string. Now get someone to hit the shelf, either with their hand or with something like a wooden spoon. How does it sound? (Warning – you’re in for a bit of a surprise!)
Why does the shelf sound so loud? How are you hearing the sound waves coming from it? Can you think of another fun experiment (using two paper cups and a long piece of string) that uses the same principle?