Oscilloscope app

Turns out I have a sound oscilloscope app. Here's me whistling. 4 cycles in 3ms means T=0.75ms. Frequency = 1/0.00075 = 1300 Hz which sounds about right. 

Under the M6

I got under the M6 at Carnforth. Not surprisingly the thick concrete is a decent sound insulator. 

Porphyritic granite on the Pentland Road

Hello There's a cutting on the Pentland Road about 2 miles east of Carloway with an obvious vein of big crystal granite in it. Looks like it has intruded  between earlier layers. BGS viewer suggests a vein of Uig Hills - Harris Igneous Complex which could be around 2 billion years old.

The phenocrysts are very like those in Shap granite. 
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But it's quieter inside the car!

Sat inside the car it is 10dB quieter. 

Motorway noise

From right by the motorway. In the 80s of decibels. 

Snowshoes!

These are how snowshoes were in old physics books. They are on the wall of the Tiso cafe in Perth. My feet are approximately 25cm long by 10cm wide. Total area of both feet = 500 square cm. One snowshoe looks to be made of 2 triangles that are 30cm x 30cm and 70cm x 30cm giving area of one snowshoe as 1500 square cm. Total area of both = 3000 square cm. So with the snowshoes the pressure is 1/6 of what it would be. I still find it hard that they are not solid. How does the mesh work?

Not a sundial!

I have got so used to public sundials that I was confused by this. The "gnomon" points east. Then I realised there were no times on the seats.And then that the seats were on the wrong side. Whoops! I'm getting conditioned. 

How long do rainbows last?

This year I am trying to count the number of rainbows that I see. Sometimes the shower stops and the rainbow disappears only for it to start again in roughly the same place a couple of minutes later. Is that a new rainbow or a rainbow that has been paused? There was one part-rainbow that endured for over 10 minutes. There were a series of rainbows that followed the one above and due to the lengthy gaps between the showers, the position of the sun had shifted which meant you could tell the rainbow was not aligned the same way over the loch. Rainbows in waterfall spray can presumably last all the daylight hours and must subtly shift orientation as the sun moves. Philosophically, is a rainbow even a thing at all? Anyway, the questions on ephemeral phenomena are keeping me entertained.

Solar powered!

This truck intrigued me. I wondered if it were a portable solar power unit. But looking at the other side, I wonder if it is actually a solar-powered advertising display. 

Coldest house in the country?

If this cottage really is at 17 Kelvin, then it must be the coldest. Not quite cold enough for the weird quantum properties of liquid helium, but close. 

Further away from a wind turbine

Now about 200 metres away. 

Definitely quieter on average - quiet enough to pick up kids on bikes behind! 

Wind turbine loudness

I stood this close to the turbine and used the dB meter. 

60dB is like the gale through the poplar tree. I wondered if the time interval for the large scale oscillations matched the turbine's rotations. 10 turns in 20 secs means time period is 2 secs. It doesn't match. 

Headphone volume

There was an article in The i on Monday about an epidemic of tinnitus. It links it to prolonged headphone use at high volume. Over 85dB for long periods is bad. It suggests using maybe 60% of full volume on your device to avoid this. I tried my dB app on my headphones. Not sure how good the reading is but it is mostly in the 60s.

Fight gravity!

I loved this car sticker. In a sense, just standing up is fighting gravity. I suppose it means "doing work against gravity" and that is how I have gravitational potential energy. 

Weighing the length

I've been knitting hearts that can be filled with stuffing. I don't have much wool left and was wondering if I had enough wool to knit the two halves. I normally measure length but I don't know how long a section I need.

I'm a bit late to the party on this one but I realised I should weigh it instead. I used the empty tub to get over the low mass cut off - it won't read below 10grams though after that the resolution is 1gram.

And there is enough for the two halves. So an odd bit of metrology.

Magnet recycling

There is a good piece in this month's Physics World about the recycling of rare-earth magnets, citing their roles in wind turbines and electric car batteries. It states that 259 million hard disk drives for computers were shipped in 2021. They tend to go to the tip every few years as a new computer is needed. I have extracted several of the magnets to play with. Previously long-loop recycling was used and the whole thing was broken down, the rare earths being recovered as oxides. Energy is then needed to convert the oxides back into metals before casting alloys, reducing this to powder and then turning the powder into metals. Under a new short-loop process the rare-earth alloys break apart to form a powder after treatment with hydrogen. Much less energy is needed so if it scales up well, this process is probably the future!

How loud is the storm?

I've posted about the sound spectrum of the wind in this big tree but now I've got a dB meter. We were sat in the greenhouse sheltering from the wind and Storm Kathleen was raging. Peak volume from the tree was over 80dB. Some sources have that as being "busy traffic", which seems about right.

There were quiet lulls as well. Interesting to note that these lasted about 5 seconds.

Energy in petrol

This wrecked exhaust silencer shows the energy in even a small amount of petrol. An Internet search reveals varied answers but one gallon of petrol contains the same energy as over 10 sticks of dynamite. This has led me to find more information on the energy density of fuels. This site gives diesel as containing more energy per litre than gasoline whereas this one has them about the same for energy per kilogram. This is because petrol is a little less dense than diesel. That said, it is litres that I put into the tank, not kg. I was also interested in the Gasoline Gallon Equivalent. 

Thinking about cloud streets

At Silloth the wind was coming in from the right. The cumulus clouds formed distinct lines. But are these cloud streets? This site seems to imply something closer and more tubular. However they seem to tie in with the description of formation. 

Calibrating my barometer

You are supposed to wait until there is a settled high pressure before adjusting but that hasn't happened in the last two months! I have set it to the Carlisle Airport figure given on the BBC Weather website. It seems to be staying about right. We were wondering whether modern double-glazed houses would affect the readings. I can't find anything on that but did find this site about where to put them. It is on an outside wall about head height and nowhere near a radiator so that should be right.

Euphotic zone data

 

I found this data at the aquarium in Maryport

I put the depth and intensity data into a spreadsheet. I'm guessing that light intensity will fall exponentially with depth in the form I = B.exp(-kd) where B and k are constants.

This seems to be true because I get a straight line.

Mercury maximum elongation

My book told me to get out at 7.30pm to see Mercury. The arrow shows Jupiter. Mercury was in the circle but the sky was to bright there for it to stand out in the photo. It has led me to find out what elongation means. It turns out that it refers to an angle. It is the biggest angle between the Sun and the planet as seen from Earth, so I suppose it must make it seem furthest from the Sun and in Mercury's case, makes it easier to see.

Testing the bin lid

I realised I have a dB meter on my phone. The bin is rated 89dB so not far off but my conversation was this loud! 

Comparing electricity supply sources

 It must be mandatory now to show sources on bills. Here are a couple I've been shown:

The second makes a point of being 100% renewables.

The bottom of a lightning conductor

 

I noticed that the lightning conductor was double thickness at the bottom - made of two parallel strips. I wondered if that was a standard feature but I haven't been able to find anything. However I did find this brilliant article. I hadn't considered what happens below the ground. So the system needs to take the current away from the building. In this case I'd hope towards the graveyard because directly away from the building was towards a house a few metres away! 

Glow sticks

There were glow sticks at Laura's party! I've always known that flexing the case breaks a chemical container inside allowing two chemicals to mix. Looking up the details here has got me doing some thinking. It says that the reaction is exergonic. This seems to be because the reaction is at constant temperature. The graph seems similar to the one I taught for exothermic reactions but they would release heat and presumably the temperature wouldn't remain constant. The energy released seems to excite a dye compound, meaning that the electrons go up energy levels. They de-excite by releasing a photon and if the dye is chosen so that the energy levels produce photons that lie in the visible range, we have a glow stick. Would we still call them glow sticks if there were photons released but not visible to the human eye?

Sensing the temperature

There is a brass-coloured cylindrical piece of metal clipped to the back of the heater. It is then attached to the thermostat control by a long bare piece of wire.

Somehow this must be sensing the temperature behind the heater. The mechanism sounds like a bimetallic strip kind of sensor. Perhaps the long metal wire is conducting heat here not electricity!

Increasing the surface area

This electric wall heater has two heating elements. The device has a switch that toggles between "half" and "full" ie one element connected or both. There are thin metal plates that sit perpendicular to both, with the elements going through them. These are to increase the surface area. The idea is that when the air touches the hot metal, there is transfer of thermal energy by conduction. The more metal that is touching the air, the more of this can happen at once and the faster the air heats up. The air expands, becomes less dense and rises. This allows colder air from below to move in to touch the plates.

Heisenberg on In Our Time

Lord Bragg of Wigton has a big interest in Physics and has done a lot to promote the subject. Heisenberg was the subject of a recent In Our Time. Towards the end, a contributor describes starting out to draw a wave as a series of points. When you draw the first point, you know a lot about the position. But you need to add more points in order to figure out the wavelength. With more points, you know less about the position. Hence particle and wave properties cannot be fully known at once.

Another lichenometry data point

It occured to me that the slates on this roof are also a way of measuring the rate of growth of the type of lichen that grows on the cemetery wall, which is half a mile away. The slates are 75 years old. So this shows that the lichen is increasing in diameter by about 2mm a year or 1mm in any ditrection.

Dark Side of the Car

I lived this vehicle. The image is one of the first bits of Physics that I remember. My Year 9 teacher was at pains to point out that the colours should be split in the middle of the prism too and not white. 

Beautiful Belt of Venus picture

 APOD had a fab picture last week which went beyond just the Belt of Venus. More sections of the sunset sky to examine and understand now.

Wheelie bin decibel level

I don't know why I'd never noticed before but I was amazed to notice that the wheelie bin had a decibel rating. It turns out that it is a warning about the noise made when the lid slams down. See here. There are lots of decibel scales on the Internet. It suggests that this is somewhere between a loud truck, a shouted conversation and a hairdryer. One difference is duration - the lid slam doesn't last long.

Potential well in Dalby Forest

I was really impressed by this structure in the adventure playground at Dalby Forest. It really does look like an inverse square potential well. 

Situated in the outer surround, it is a brilliant representation of the nucleus and alpha radiation. The alpha particles would have to use quantum tunneling to escape through the sides of the potential well.

Shap Granite erratics at Robin Hood's Bay?

We found these two boulders on the beach at Robin Hood's Bay. They could well be glacial erratics. There was always a stone opposite the Radcliffe Science Library in Oxford that was a glacial erratic of Shap Granite brought back from Filey, I think. It shows ice moved in that direction. I suppose they could have been brought as sea defences but sea defence boulders are usually all of the same type. Also the coast is not being defended!