Finely balanced on the new Forth Road Bridge

The new Forth Road Bridge is taking shape. The support columns are in but not joined. They are building the road deck outwards from each one and eventually the sections will join up. Notice that the method involves balancing the deck equally on each side. There will be no resultant moment so the column will not fall. Each section is a cable-stay design. The diagonal stays have a vertical component compressing the concrete in the column. Concrete is strong under compression. The horizontal components are equal and opposite pushing in on the column from left and right. The final thing to note is the weird picture effect. The car was moving from right to left. The tops of the cones are bent out of shape. I think it suggests that the camera reads the CCD row by row from top to bottom because the bottoms end up lined up with the column, The cone would not have been thus aligned when I first started taking the photograph.

Wilberforce Pendulum: a chance encounter in Stonethwaite, Borrowdale

 We didn't even know that there was a church at Stonethwaite but we went in for a look and found the above memorial on the wall. I'd never heard of him but looked him up https://en.wikipedia.org/wiki/Lionel_Wilberforce I'm always impressed by anyone who worked with JJ Thomson but I'd never heard of the Wilberforce pendulum. Here's a film of it in action https://www.youtube.com/watch?v=S42lLTlnfZc It is a couple oscillator the sends the energy from up and down vibration to rotational motion and back again periodically. I want to make one now! The churchyard also has the grave of fell-running legend Bob Graham!

Alexander Buchan, isobars and Loch Leven

I had never heard of Alexander Buchan but it is claimed that he was the first to make a scientific weather forecast based on weather charts he developed. Iso in Greek means the same. Isobars are lines that join up places with the same air pressure. They look like contours on weather maps. He was the first person to draw these. He was from a village on the other side of Loch Leven under the impressive basalt outcrop in the photograph. I was pleased to hear that he was a key mover in the building of the Ben Nevis weather station. Read more about him http://www.weathercast.co.uk/weather-news/news/ch/23ba64ba62807a6e3d649985141b30d3/article/alexander_buchan-1.html and https://en.wikipedia.org/wiki/Alexander_Buchan_(meteorologist)

Low Ling Crag roche mountonee on Crummock Water

I'd been wanting to visit this feature on the far side of Crummock Water for years. Now I've been. There has been some argument on the Internet about whether it is a roche moutonee. What's the evidence? They form when a glacier goes over hard bedrock. The glacier here would have been flowing from right to left. The glacier smooths the approach side into a smooth ramp. Coming over the top, the pressure melts some of the ice which then runs into crack in the rock. This water then refreezes and gets pulled by the glacier. This rips the downstream side into a crag. Well, that seems correct with what's in the photograph. There is a diagram here https://en.wikipedia.org/wiki/Roche_moutonn%C3%A9e#/media/File:Roche_moutonn%C3%A9e_eng_text.png As to why ice melts under pressure, that's another story...

Radioactive decay dice

Today we did the experiment that models radioactive decay. We have wooden cubes with one side coloured in. All 30 dice are thrown together. The ones that fall with the coloured-in side upwards are deemed to have decayed and are thus removed from the set. The rest of the dice are thrown again and so the pattern repeats. We count the number of dice left in each time and plot a graph of that against throw number. The result is an almost exponential graph but with a lot of anomalies because the sample size is so small. Today one team did something I've never seen before:

They stacked up the dice removed each time to make a 3D bar graph of dice removed against throw number (on the horizontal axis). In theory, 1/6 of the number of dice thrown should be removed each time. This worked on the first go because 5 is 1/6 of 30. That left 25 dice to throw and 1/6 of 25 would have meant 4 dice removed on the second go. That clearly didn't happen. But the trend is towards an exponential decay graph. A much larger number of dice would be needed to get a truer pattern. I thought this was a wonderful way of presenting the data. :D

Inside an old hard drive

I took apart an old hard drive. The silver disc that is reflecting my camera is called the platter. This is made of a non-magnetic material like aluminium or ceramic with a thin magnetisable layer on the surface.

 The actuator arm has a very tiny electromagnetic coil on the pointed end. It is called the read-write head. If current runs through this, it acts as a magnet and magnetises sections of the platter below. When reading data, the magnetised sections moving below it cause electromagnetic induction to take place. An emf is induced which causes a current to flow in the read-write head and the computer can pick up the data.

 There are strong permanent magnets in the corner with what is called a voice coil between them. When current flows in the voice coil, it attracts or repels from the permanent magnets and can thus move.

The magnetic circuitry must be very sensitive and will deserve testing next time one comes my way.

A couple in Grizedale Forest

We found several of these on a walk in Grizedale Forest. Turning forces are given several different names most notably moment and torque. This is a COUPLE. A couple is when two equal but opposite forces, one on either side of the pivot, push the object round. To calculate the size of the couple you do one force x the distance between the forces. Since the individual moments of each force = force x distance from pivot, but the distance between the two forces is twice the distance from each one to the pivot, the formula for a couple is just the sum of the two moments.