Fluid dynamics in Borrowdale

 The two pictures above show the serenely calm waters on one side of the track near Rosthwaite.

Hard to see on this photograph, but on the other side of the track, barely 2 metres away, the flow rate was quite substantial. The pool must act as a header tank but the drop can only be maybe 10cm. I had a poke at the outflow. It might have been 30cm by maybe 5cm max. Here's a simplistic attempt at analysis using some school equations. Loss in gravitational potential energy = gain in kinetic energy. mgh=0.5mv^2. Put in h=10cm and you get v=1.4 metres per second. Volume flow rate = Av = 0.30 x 0.05 x 1.4 = 0.021 cubic metres per second. The entire volume of the header pond might be 3m x 1m x 0.05m = 0.15 cubic metres meaning that the pond would be drained in 7 seconds if there were no water flowing in. That sounds very unlikely so the calculated flow rate must be too high.

Watching the rain at Lingholm

 We were having lunch in the greenhouse at Lingholm when it was pointed out that the clip on the centre of the glass produced a much wider and therefore clearer flow of water.

 The central drip started from part of the window opening mechanism much higher up. This ran down the centre of the pane.

Somehow the outside of the clip seemed to be bringing together narrow beads of rain and joining them to make wider sections. The narrower sections are more opaque because the curvature of the water is greater and so it has more of a lensing effect on the light by refraction. Lots of little sections of this close together acts like frosted glass. If the same water is spread more widely in a thinner layer, it refracts less and is easier to see through.

Concrete piles in Blackpool

 The random selection of vertical concrete columns in the middle distance are called concrete piles. The issue here is that the solid rock will be under a layer of weaker soil, possibly quite sandy being near the beach. All you need to know about piles is here http://www.understandconstruction.com/pile-foundations.html It looks like these were probably pre-cast and then driven in with a pile driver.

Then it looks as though the foundations of the buildings are laid across the piles. The concrete is poured around the steel frame to make reinforced concrete. This is because concrete is strong when loads are compressing it but is weak and cracks easily when stretched. The steel provides the resistance to stretching. The combination of concrete and steel is lighter and cheaper.

Automatic Weather Station at Honister

We found this weather station on Fleetwith Pike. I looked up the brand https://www.vaisala.com/en/products/instruments-sensors-and-other-measurement-devices/weather-stations-and-sensors This station doesn't seem to have a wind speed recorder and there is no obvious rain gauge. I was thinking that weather records up here would just be a nice thing to have, but then I found that they might be of use in modern climate research https://www.researchgate.net/publication/268469950_Extreme_rainfall_in_Cumbria_November_2009_-_an_assessment_of_storm_rarity Thus far I have only read the abstract but it promises to show that even short term rain records can help to estimate storm frequency in uplands.

Coin machine in Blackpool

I am endlessly fascinated by the Physics of these machines. This particular machine has the biggest overhang I have ever seen. I know that coins are fixed into the lip to create the start but even so, the the way that each is stacked with others supporting from above by overlap is impressive. This must create an opposing moment to stop the coin tipping over the edge.

A model of an ionic compound

We made 3D models of a simple ionic compound using jelly babies and spaghetti. The two different colours of jelly baby represent positive and negative ions. The spaghetti represents the electrostatic attraction. If you are tempted to do this, the brittle spaghetti caused quite a mess. This could be NaCl where the charges are the same and the ratio is 1:1. I looked into modelling something like CaCl2 but the pictures I found of the ionic arrangements were hard to make.

Stretching a polymer

Wanting an experiment to illustrate the teaching on bonding in polymers, we can strips of a bin back. The hypothesis was that for the same load, double the length of strip will have double the extension because twice as many bonds will be being stretched, like a longer chain of springs. The data was very messy. One problem was that given time the knots started to unravel under tension. Another problem is that the hypothesis is probably wrong, although the results did not give us a consistent pattern so that we could tell. Certainly with rubber bands, the chains are tangled by side branch bonds. This makes it harder to stretch at first. Once untangled, it is easy to stretch them until they are straight and only then do the actual bonds get stretched.

Quantum Biology TED talk

Jim Al-Khalili has done a lovely TED talk on the areas of research involving the application of Quantum Mechanics to living systems https://www.ted.com/talks/jim_al_khalili_how_quantum_biology_might_explain_life_s_biggest_questions?language=en

Explaining interference and path difference

We have these lovely perspex waves to illustrate double slit interference.

At the point illustrated above, a trough on the upper wave coincides with a trough on the lower wave so there will be constructive interference and a fringe will form. The bottom wave has gone two whole wavelengths less to reach this point. I think that this is a very graphic illustration of path difference. I started from the central maximum and moved out, putting dots on the table to show each fringe.

A functional model of the ear

I built this functional model to try to get my class to understand the functioning of the ear. The funnel is the pinna which directs sound waves from the air into the head. The tube represents the ear canal which takes the air vibrations deeper into the head. The cling film represents the ear drum. This converts vibrations in a gas to vibrations in a solid. The pen represents the ear bones. These amplify the signal, which is still in the form of a vibrating solid. The balloon full of water represents the cochlea where the solid vibrations turn into vibrations in a liquid. The liquid brushes hairs in the cochlea which turn the vibrations into a nerve message, hence the wire.

Combe Gill Hydro in Borrowdale

Coming down off Rosthwaite Fell we spotted the tell-tale signs of another hydro project. This is it: https://www.nationaltrust.org.uk/borrowdale-and-derwent-water/projects/combe-gill-hydro-power-project-diary and https://consult.environment-agency.gov.uk/psc/the-national-trust-29470-28031/supporting_documents/29470%20Design%20and%20Access%20Statement.pdf It will supply 200 homes. Suppose they paid £500 a year in electricity bills. That would raise £100000 a year. I can't find how much it cost to install. Given that some of the bill goes to maintain the National Grid and other such, and also that it is costing £6 million to repair the Keswick to Threlkeld cycle track, I suspect it will take some decades to pay back this project. I was interested to see that they are using a Coanda plate for the stream intake. I have posted before about the Coanda Effect http://wigtonphysics.blogspot.com/2016/10/coanda-effect-and-toilet-at-watchtree.html but you can read about the application to hydro plants at https://www.powerspout.com/products/diy-coanda-intake-screen

Flat screen TV diffraction grating

Looks like I'm not the first person to have noticed this about flat screen TVs. https://www.physicsforums.com/threads/strange-optical-phenomenon-diffraction-or-something-else-solved.867358/ I'd have thought that it was behaving like a CD and being a reflection grating. Perhaps not. I hadn't even thought about the X shape. I have posted before about net curtains giving a + shape diffraction patterns which is due to horizontal and vertical slits in the same material. Does the X relate to the alignment of parts of the screen?

Scilly power station

I'm always interested in how remote islands are supplied by electricity. The answer in the case of the Isles of Scilly is that there is a single cable connecting them to the mainland. That can get broken - https://www.bbc.co.uk/news/uk-england-cornwall-39166226 We were told that the station in the picture is the diesel backup. https://www.westernpower.co.uk/projects/isles-of-scilly

Tempus Imperator Rerum

Physicists love a good quotation about time. On the grave of our former Prime Minister Harold Wilson, which you can find at Old Town on St Marys, it says: "Tempus Imperator Rerum". Time is the ruler of everything. Perhaps this should be a fundamental law of Physics.

Not a parabola at Blackpool FC

We went to see Oxford United at Blackpool. The sprinklers that come up out of the pitch were amazing. If an object is fired at constant speed at an angle to the ground then it should go in a parabola. This isn't far off but look at the way it only goes a certain distance and then falls. The water droplets must be subject to air resistance hence the shape can't be parabolic. It reminds me of the track of an alpha particle in a cloud chamber. The particle loses energy by successive collisions and then the final collision makes it bend as it loses its final energy, gains electrons and becomes a helium atom.

How long is that cirrus cloud?

I read here https://en.wikipedia.org/wiki/Cirrus_cloud that in certain circumstances a cirrus cloud can be a long as a continent. But what about these? My finger represents 1 degree. I'd say that these clouds subtend 10 degrees. We are in a temperate region so let's say that the clouds are at 6000m. By trigonometry, that puts the clouds at 1km long.