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01. PLANET SCIENCE PARENTS FUN PACK
Need some eggy experiments, games, or things to distract the kids from fighting on long car journeys...? No problem. Here's where you'll find just what you need: It's a year old, but it hasn't lost the old holiday magic...  |
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| 02. HOLIDAY AWKWARD QUESTION Last week's question was: Today was the very last snowfall of winter and the weather forecast for tomorrow is bright, warm sunshine. Pete desperately wants to build a snowman that will last but he's not sure what to do. He has to make some quick decisions before the snow is gone, a short fat snowman or a tall thin one - and what about clothes - should he put a coat and hat on it? Worked it out? OK, here comes the correct answer: Unless Pete has a large freezer he is going to have use a bit physics knowledge to help his snowman survive the warm weather. The Sun warms the snow, but it only hits the outside, melting the thin layer on the surface. Inside the snow is insulated, so the thicker the snow the longer it takes for the snowman to melt. A short, fat snowman will therefore melt more slowly than a tall thin one. This is all about surface area to volume ratio... the larger the surface area compared to the volume the quicker the snowman will melt. This ratio is more often used for heat loss: for example, a baby has a very high surface area compared to its volume so it cools very quickly and must be kept warm. An adult, however, has a much smaller surface area compared to their volume and so cools much more slowly. Spheres are the best shape possible for minimising the surface area - so if Pete builds his snowman from several large snowballs the snowman will survive the longest. As for clothes, we tend to think that clothes keep us warm, but surprisingly, they keep us cool too. They act as insulators which stop heat moving from inside to outside, and also from outside to inside. The clothes trap still air around the body so heat loss (or gain in the case of the snowman) due to conduction and convection is reduced. So it's a good idea for Pete to put a coat and hat on his snowman. There is another method of heat transfer though, called radiation. We can feel the heat radiating from the Sun on our faces for example, and this heat radiation is disastrous to snow. The colour of the coat and hat becomes important when we think about this heat radiation, as black objects absorb heat, while white objects reflect it away. If Pete can find a white coat and hat, the heat from the Sun will be reflected away. Better still, he could coat his snowman in aluminium foil to reflect even more heat away - very space age! |
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| 03. A NOT VERY SCIENTIFIC AWKWARD QUESTION ... designed to drive you mad (unless of course you know the answer...) Two boys fall in a hole, and when they come out one has a clean face, andone a dirty face - but it's the one with the clean face that goes to wash himself. WHY? |
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| 04. AND FINALLY ... A rooster lays an egg on the roof of a barn... Each side of the roof has a 90 degree angle and windspeed is approximately 15 mph blowing in an eastern direction. The egg is laid at the front part of the roof, which has caved in slightly due to the weather. Because that part of the roof is caved in, it has a small 45 degree lip on it, which is more than elsewhere on the rest of the roof. So, which side of the roof will the egg roll off of: the one with the eastern exposure, or the one with the western exposure? Answer: Roosters don't lay eggs. Ha ha!  Recovered?! Ok, the newsletter will return next week, when amongst other things, we'll be unveiling our new Pre-Schooler and Under-11s online resources... If you'd like to contribute any ideas or share any information with other newsletter readers, please send an email to Anne McNaught on anne@planet-science.com. Have a great holiday! |
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