L6 Estimation question: how high do they fly above Wigton?

If you make this picture bigger, you will see a small white dot just to the left of my little finger. That's a plane high over Wigton heading for America. Imagine a triangle from one side of my little finger down to the camera lens and back up to the other side of my little finger. The camera was about 60 cm from my little finger. Show that the angle in the triangle is about 1 degree.
So my little finger represents an angle of about 1 degree when held at arm's length. Compare my little finger to the plane. If my little finger is worth 1 degree, what is the plane worth?
Find out how big an aeroplane and use the triangle idea to calculate how high the aeroplane is.

BBC 2 Horizon programme on the multiverse

There was a wonderful episode of Horizon last week on the state of multiverse research. This is the idea that there is more than one universe out there. I was familiar with the quantum idea that when a yes or no decision is made, the universe splits in two to allow both possibilities to exist at the same time. This is an alternative to saying that things remain in a state of quantum uncertainty when you are not looking at them: Scrodinger's Cat is the usual explanation. But the programme also goes into cosmological views on the multiverse. It seems somehow more convincing when there are competing models... Here's the link, valid for a while yet: http://www.bbc.co.uk/iplayer/episode/b0695t56/horizon-20142015-17-which-universe-are-we-in

Circus balancing act

Really impressive balancing act at Zippo's Circus. It must be the case that the line of action of her weight down from her centre of gravity must act through her base area or else there would be a resultant torque and she would topple. Hands give a bigger area so she balanced on top of a pole which would make it harder. She then raised herself by catching and adding bricks under each hand, one at a time.

Flying a kite in Silloth

 After the observations of big kite and little kite on Silecroft beach I resolved to make some measurements. Tonight I got a spring balance to measure the tension in the string. The 1N reading was probably a bit low, with the spring balance being upside down. I felt the tension in the string and then felt the newtonmeter - felt more like 2 Newtons in truth. I estimate the angle of the string as 45 degrees to the horizontal. The kite itself leans forwards - the string is not perpendicular to the kite at the top so I've assumed it was at an angle of 40 degrees above the horizontal. I measured the kite - 69cm by 59cm so area was 0.41 square metres. I assumed the density of air as 1 kg per cubic metre. I calculated the force of the air on the kite by assuming a component of the wind normal to the kite and that the air stops dead when it hits the kite. I then used Newton's Second Law as rate of change of momentum of the normal flow of air hitting the kite. My method is shown below.

I put in the numbers and got 3.6 metres per second as the wind speed. That's 13 km per hour or about 8 mph. That doesn't sound too bad. The wind speed was too low to fly the bigger kite. Will repeat with a stronger wind and try to measure the angles more accurately. Thanks to Adam for holding the kite!

Root Mean Square in Wigton

I spotted this sign today. The letters R.M.S. are important in Physics.Think about the molecules in the air. The distribution of velocities is random. That means that there will be as many going left at 6 m/s as there are going right. We could say left is 6 m/s and right is -6 m/s. So the average velocity of all air molecules would be ZERO. That's nonsense. So what we do is SQUARE all of the velocities. That removes the minus signs so we get a sensible non-zero MEAN. To get the number back to normal size we have to take the ROOT. Put backwards, that's ROOT MEAN SQUARE - RMS.

Update on the wave-like pattern: Aira Force

This is Aira Force, much beloved of William Wordsworth. Foam bubbles from the waterfall travel across the pond and gather in the corner as shown below...

The shape and structure are exactly as seen last week above Hayeswater, except that there is no gap between the semi-circular wavefronts. I will look out for more examples.

Structure: abstract at UEA

We went to see an exhibition of abstract art at the Sainsbury Centre at UEA in Norwich. The exhibition featured the work of John Golding, as shown on their leaflet. The commentary emphasised the way that he gives structure to an otherwise abstract space. That reminded me of several things in Physics. One is the way that physicists go on about structure in the Universe. It looks random to me but the way that galaxies are grouped into clusters throughout space is significant. A second is the Hertzsprung-Russell diagram for the lifecycle of stars.

I was told that the pattern was amazing. I wasn't impressed first time I saw this plot of the brightness of a star against star type. I'm used to straight line graphs/ And yet there is a clear structure here. Golding's paintings remind me of this.