Welcome back to Homework Club. Well done to anyone who worked out last week’s teaser about why the Eiffel Tower grows six inches in summer, and leans away from the sun. It’s because metal expands when it’s heated. The side of the tower nearer the sun expands slightly more, and so ‘pushes’ the structure in the other direction. We’ll have another amazing Eiffel Tower fact next week – in the meantime here are this week’s fun facts to tee up your home schooling …
The word ‘koala’ comes from the Aboriginal word ‘gula’, meaning ‘no water’ – the marsupial rarely needs to drink, as the eucalyptus leaves it eats contain lots of water.
BONUS FACT: koalas eat so many eucalyptus leaves that up close they smell like cough sweets.
0.9 recurring equals 1.
‘But it can’t!’ you say. ‘It begins “nought point …” So it has to be less than one.’ That’s an understandable gut reaction. However, try thinking of it this way:
One-ninth equals 0.1 recurring (0.111111…. going on forever) Your gut has no problem with that, right?
Now multiply both sides of that equation by nine.
1/9 x 9 = 1
0.111111 … x 9 = 0.999999…
Therefore 1 = 0.999999 …
Three of the first US presidents died on July 4 – and two of those were in the same year. James Monroe, the fifth president, died on Independence Day 1831. John Adams (the second president) had died on July 4 1826 (the 50th anniversary of America’s independence). His last words were an expression of relief that his friend, the third president, was still alive: ‘Thomas Jefferson still survives’. However what he didn’t know was that Jefferson had died several hours previously.
There are only two ‘doubly-landlocked’ countries in the world – that is, countries which are surrounded only by countries that are themselves landlocked. They are:
– Liechtenstein (surrounded by Switzerland and Austria)
– Uzbekistan (surrounded by Afghanistan, Kazakhstan, Kyrgyzstan, Tajikistan and Turkmenistan)
‘Devil’s advocate’ (someone who argues against a case to test its strength) was originally a position (Advocatus Diaboli) in the Catholic Church. It was held by a lawyer who spoke against the canonisation of those proposed for sainthood.
Science and nature
In 1709 William Derham, the rector of Upminster, used his church (St Laurence) to estimate the speed of sound. He stood at the top of its tower, and, through a telescope, watched an assistant fire a shotgun several fields away. He then used a half-second pendulum to measure the time it took for him to hear the shot. The experiment was repeated with the gun fired at different locations. In each case Derham knew the exact distance between the gun and the tower. Averaging out his results, he concluded that the speed of sound was 1,116 feet per second. The accepted answer today? 1,115 feet per second.
If you’ve got access to a large enough space at the moment (for instance a park), take a hammer and something you can hit (say, a metal dustbin lid) and get your assistant (i.e. family member) to watch you hit it. See how far away they have to stand before there is a gap between them seeing and hearing the strike.