• scissors
    May 14th, 2013ImogenUncategorized

    Wonderful Water Thing #1

    From my previous post, you may have realised that my house isn’t that warm. The place I’m living in was built in the 18th Century and isn’t exactly airtight, but water vapour from cooking and breathing still builds up inside the house. The thing is, cooler air holds less water, so when the air reaches a cooler surface, water falls out of the air and sticks to the cold surface. This appears as condensation on windows.

    This is how clouds are made too. Air gets cooler as you get further away from ground level, so at a certain distance from the ground the air will reach a temperature where it can no longer hold the water vapour dissolved in the air, and the bits of water that had been dispersed in the air start to stick together and reflect light. This makes them appear white. The height at which this happens is known as the cloud base. Window condensation is basically a cloud stuck to your window, so that’s actually pretty exciting.

    Watery Wonderful Thing #2

    I was driving home from work today and there was a humungous rainstorm. I was seriously glad I was not on my bicycle, or I think I would have dissolved in it. The sunshine with the rain made a rainbow pop up but it was so low in the sky I could see both ends through my windscreen. This realisation did nothing for my concentration. The thought of pots of gold hiding on the golf course is enough to make a girl lose her hubcap.
    It turns out that the height a rainbow will occur at is linked to the time of day. A rainbow is essentially a circle, and the circle’s centre is at the opposite point in the sky from the sun. At sunrise or sunset, this point will be on the horizon, so the rainbow will be at its highest. As the sun rises, the bow’s centre gets lower so that its centre is below the horizon and to us it looks smaller. The rainbow always appears to have the same radius of 42˚, so when the sun is 42˚ high only the top of the rainbow is visible over the horizon.

    I say appears, because the rainbow is not fixed in space, as you will know if you’ve ever tried to reach the end of one. It really is just a mirage, you can never get any closer to it because it’s not really there.

    Wonderful Watery Whatsit #3

    The third amazing thing is very simple and I noticed it when I was soaking my rice this evening in a few centimetres of water (this is pretty low tech). I was moving the saucepan back and forth waiting for the kettle to boil and I realised that as the water moved, the base of the saucepan appeared to be rocking up and down.

    Rainbow over the park

    Today's rainbow from the same window

    As the bigger mass of water came over a spot, the water refracted the light more. The effect of this is make the distance between us and the object appear smaller, so the base of the saucepan appears closer the more water is over it. As the water rocks away the light is refracted less and the base appears further away again. Wibbly wobbly saucepan! It’s like magic. I recommend a big saucepan for the best effect.

    There are like a zillion more amazing things that water does. This is just the tip of the iceberg (ahahaha).

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  • scissors
    March 1st, 2012ImogenUncategorized

    Noble, gaseous air. Can’t live without it, can’t walk over it. If you’re not an Olympic swimmer then you probably spend most of your waking hours moving through air. Therefore, as well as serving a perfunctory functional purpose, a bath can be a bit of respite. A change of scene- or state, if you will. However, next time you have a bath, there’s no need to just sit there! Did you know that there is a whole host of micro-experiments you can try out, all from the comfort of your lavender scented water? Here are my top 3 favourites.

    1. Wave Interference

    Unless you are some sort of bath-drawing pro, there’s always some essential water mixing to be performed. This is a perfect opportunity to make something constructive. Or destructive, if you so wish. Make some waves travel down the bath then watch as they are reflected by the end of the bath and travel back on themselves. Where two peaks intersect you will get constructive interference and the wave will be bigger and splashier. If a peak and a trough meet then they will cancel each other out and you’ll get a ‘node’, or flatness.

    This is exactly how noise cancelling headphones work: the headphones listen to the ambient noise around you and play you a sound wave that is the exact opposite to the noise. The ambient sounds are cancelled out by the new wave and so you don’t hear it. This is why these devices work better for environments with constant noise levels- when you are on an aeroplane, for instance.

    2. Manual Airfoil

    Technically a waterfoil, but that sounds like a duck or something. If you make a cupped shape with your hand under the water and sweep it along your leg, you will feel a suction pulling your palm towards your lallies. This works best if you hold your hand as close as possible to your leg without actually touching it.

    Your hand is moving through the water like the wing of an aeroplane moves through the air. As the water moves over the curved back of your hand it has to travel faster than it does under your flat palm. The slow moving water under your hand creates a region of lower pressure, effectively sucking your hand in that direction. So really, planes don’t fly, they’re just suckers.

     self portrait

    3. Living on Jupiter

    Ok so you’ve made waves, swooshed your hands around, splashed lots of water on the floor, and maybe got a bit cleaner too. Before you turn into a complete prune it’s time to get out, but you’re just so relaxed and comfy. Instead of arising abruptly and possible getting a head rush and falling and hitting your head on the sink and having a brain haemorrhage (don’t say I didn’t warn you), try number 3 instead. Lie in your bath and take the plug out. As the water line drops further, you will start to feel strangely heavy. Your muscles have had a bit of a holiday, aided by the buoyancy of the water. Now the water’s gone there is no upthrust, only a force of approximately 1 Newton per Kilo pulling you towards the centre of the Earth. Now, don’t you feel like you’ve just come back from the moon?

     

    If you like to take some refreshment at bathtime then be sure to check out my other blog post Slurpy Bath Tea, it’s essential reading on the topic.

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  • scissors
    August 4th, 2011ImogenUncategorized

    This week’s science question comes from my dear mama. She asks “Why do I dribble when I sip my champagne in the bath?”.

    Just for clarification, the champagne is wishful thinking and my mum is much more likely to be drinking tea. Either way, why is it that one who knows much better can’t help getting tannins in her bathwater?

    The answer is surface tension. Alike molecules­­ attract and hold on to each other via cohesion. H20 is a polar molecule, so it has both a positive and negative end which means that one H20 can turn around and attract another. Water molecules form a linked surface layer which tries to resist attempts at breaking it. You can see this in drops of water clinging together on a hard surface, or that well known systematic error-source, the meniscus (for future reference, one must always measure from the bottom of the meniscus). Rivulets of water running down your window follow the path of least resistance, and this means the path that is already wet. Drinking when your face is wet elicits the same effect: water does not retain its surface tension and flow exactly where it is directed, but follows the path which has already been laid by your bubbly beard experiments.Minimise those errors!

    The solution I would suggest to my mum as she gets tipsy on her PG is either 1) dry thine face or 2) use a straw. Anything else is likely to result in a tragic loss of beverage.

     

    Is there a scientific issue you’re curious about? Is there something you wish you could hear explained simply? If so, drop me a line at [email protected], on twitter via @imogenhouse or using the contact form, and I’ll break it down for you so you need never lack the answer again.

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  • scissors
    March 29th, 2011ImogenUncategorized

    Tea Vortex

    Sometimes it is easy to find anything more interesting than the work you should be getting on with. This morning I took a break from revision to make some tea. I had to use powdered milk but sadly it 1) refused to dissolve properly, and 2) tastes weird, so I didn’t drink the resulting brew and it remains on my desk. As my mind wandered from the mysteries of dielectric materials in capacitors I developed a fascination with stirring my now-cold tea.

    By stirring the tea and then placing the spoon perpendicular to the edge of the cup I can create a mini vortex. Milk particles orbiting in the vortex have more speed than those which continue to do a full circuit of the mug. This is because they seek to conserve their angular momentum. Angular momentum is equal to the product of the radius of the circle, the mass of the particle and its velocity. The mass does not change so as the radius decreases, the velocity must increase in order to keep the angular momentum the same.

    What is concerning is that this is only my second day of revision and my exams are still 6 weeks away. I dread to think what will be entertaining me in the weeks to come. My reflection in a spoon perhaps? Perfecting my “r” rolling? Actually between sentences I am already experimenting with rotating on my swivel chair by waving my arms around like an over-intent cheerleader.

    Whatever keeps us sane, eh? I suppose I’d better get back to work.

    Oh look it’s almost lunchtime!

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  • scissors
    March 24th, 2011ImogenUncategorized

    They say that there is no such thing as bad weather, only inappropriate clothing. However, as a carefree young girl-about-town (read: impoverished student with small handbag) I happened to be tragically ill-prepared one day when the weather took a turn for the worse. As luck would have it on this drizzly day I had cycled into university. In order to retain my right to scoff at fair-weather-cyclists I felt obliged to brave the precipitation, mac or no mac and so I set off on my merry way. At least, it might have been merry if I had worn my gloves.

    For some time I was perplexed as to why my hands were getting so nippy. They were disproportionately chilly compared to the rest of my extremities but I couldn’t work out why. It was only when I got back to my house and was fumbling with the bike lock I realised that there was a very simple reason: it all comes down to evaporation.


    Mastering evaporation. (safely)

    There are two main reasons for this chilling effect (chilling where things get colder, that is. Physics is nothing scary). These are firstly, the varying energies of different molecular states and secondly, the law of diffusion. Here’s how they work.

    Molecules (with a few exceptions) are found bound in one of three states: solids, liquids and gases. A gas molecule has more energy than a liquid molecule, which in turn has more energy than a solid. This energy takes the form of tiny molecular vibrations – generally measured as heat. As temperature increases the individual molecules gain more energy and so start to vibrate more vivaciously. As vibrations grow the molecules will gradually break bonds to their neighbours. This is why as you go from solid to liquid to gas the substance becomes less rigid and more free-flowing.

    When I was learning about molecular states at school we did a practical in the playground, swinging about hanging onto each others’ elbows. As our class’s “heat” increased we were ordered to progressively let go of each other and observed how much further we could rampage as a result. If you feel a desire to experience this yourself I suggest experimenting by grasping on to a friend while you are a) standing on plastic bags, b) standing on skateboards or c) at the mercy of a small footloose child. The less random movement occurring, the greater your chances of remaining bound to your fellow molecule.

    Particles always diffuse from an area of high concentration to low concentration. This is a fundamental rule in physics, and explains why the smell of burnt toast manages to permeate every room in the house. Water on a surface is of a higher concentration than water vapour suspended in the air, so eventually the surface will “dry out” as all the water evaporates in an attempt to even out the concentrations. The surface will also be left cooler, as we have seen before. Finally, moving air increases the rate of evaporation because the concentration in the air is kept much lower than at the surface as evaporated molecules are consistently removed.

    In order to escape from a liquid and become an unconstrained gas particle, a water molecule needs to gain some energy from the liquid first. So how does this relate to my cold hands? As the tiny water droplets left my skin they took some energy with them, making my skin feel cool (because it’s just lost some heat energy). My skin then had to burn stored energy (from food) to generate more heat to bring it back up to temperature – I wouldn’t recommend hypothermia as a great weight-loss method though.

    Instinctively, we already know all this, that’s why everyone blows on soup. By huffing and puffing you increase the rate of evaporation. The greater number of particles escaping the surface means the liquid loses heat energy. This makes your food (/drink, I’m never quite sure with soup) less likely to burn your tongue.

    So what’s a similar effect? A fan in a closed room will not actually cool the room since it’s only moving air around (if anything, it’s heating the room up by creating heat via friction in its moving parts). However, if it’s blowing air at you, you will feel less hot as the moisture on your fevered brow evaporates.

    And this is why my hands were so very chilly in the wind and rain. What I really needed was a good pair of waterproof gloves to keep me warm. In fact, I have some such gloves at my disposal, but I forgot them that fateful day. Maybe what I really need is a better memory, but unfortunately neurology isn’t my speciality. In fact, if anyone would like to break down the science of remembering things for me, I would always love to learn more.

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  • scissors
    February 12th, 2011ImogenUncategorized

    This Study of Arms by Leonardo da Vinci shows the muscles in wonderful detail. You can see how far up the arm the tendons for the fingers go.

    I recently had the pleasure of going with my Dad to see Richard Thompson and band performing at the Royal Festival Hall. The concert was amazing, and from our meticulously booked seats I had a great view of RT’s playing. I was fascinated by the muscles apparent in his right forearm as he plucked and strummed. My dad tells me that Mr Thompson practices for two hours a day (even on tour!) and although his arms are not “hench” (as some of my friends back home may say) and hugely bulky, the muscles for his fingers are certainly well-honed.   As you can see in Leonardo da Vinci’s sketch, there are very few muscles actually in the hand. Fingers are controlled by muscles in the arm and the two are connected by tendons.

    Muscles make us move, but like everything else in the body they can go wrong. What I would like to know today is: what are muscle knots? After looking into the answer I find that it is actually relatively simple, they are parts of a muscle that have contracted, but not relaxed along with the rest of the muscle. Muscles can only pull (never push) so a muscle is either contracted or relaxed. A muscle fibre is made up of lots of filaments that slide over each other to create a pulling force. As the filaments overlap more the muscle becomes shorter and more compact. You can see this in action by looking at your inner forearm as you make a fist. Place another hand on your forearm as you do so and you will feel the active muscle changing shape as it contracts. When I do it my hand is also involuntarily lifted up slightly as the muscle shortens.

    So apparently, these knots are actually known as myofascial trigger points. The most common way to remove them is with massage or using hot or cold packs which will encourage the muscle to relax. You can also use electrostimulation or pulsed ultrasound (woo ultrasound!). I actually had electrostimulation while I was seeing a physiotherapist to correct my spinal scoliosis. I can inform you that it is very relaxing and feels like pins and needles.

    I can’t find much information on why these “trigger points” are painful but I make the educated guess that the pain is due to lactic acid build up as the muscle respires faster than the blood can deliver oxygen to it. This is the same source of pain as when you work a muscle very hard, for instance, when running up stairs. From my own experience, massaging a muscle knot is painful too. Does anyone know why this is?

     

    If you’d like to know more about how a muscle contractions then here is a great animation I heard about from my physiology course. Even if you’re not interested in all the fancy names (let’s face it, you’re not going to want to learn them all if you don’t have an exam on it) you might find it interesting to see how the components move past each other.

    Happy muscling!

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