Miles per litre

I'm impressed that many of my classes seem to know the fuel economy of a car in miles per gallon. Problem is that petrol is sold in litres now. As part of my quest to verify the data in David MacKay's book last summer, I started noting the amount of fuel that went into the car and the mileage. Over 5 weeks of the summer holiday, our car averaged about 17 miles per litre. Looking in the handbook, that comes between the given values for motorways and for city driving, so it sounds about right. They test their cars on rollers in a lab so I'd like to know if they factor in air resistance as well.

Join the Institute of Physics

If you are studying physics in the Sixth Form, you can join the Institute of Physics for FREE. This would look good on a UCAS form but is also a good thing in its own right. I trained as an engineer but it is through my membership of the Institute that I have come to think of myself as a physicist. They send me the monthly magazine that I put up in the lab. You would be able to access this online.
The Institute is the organisation that promotes and regulates physics in this country.
www.iop.org/16-19 to sign up!

Orbital resonance and metallic hydrogen

I've always found the planets a bit boring because they just seemed like a set of odd facts that needed explaining. A bit like the classification of animals. But Brian Cox's TV programmes are sucking me in.
Having been asked by year 10, I have been reading up on Jupiter. Can you stand on the planet? I'd never really stopped to think about its "gas giant" status. It's not all as simple as gas apparently. Although mainly hygrogen and helium (the colours are traces of other gases), the intense pressure towards its core turns the hydrogen into "metallic hydrogen". I'm just getting to grips with what this is. I'm assuming it must conduct due to delocalised electrons to earn its name. Look it up on the Internet
On last week's programme, Brian Cox looked at the rings of Saturn. Apparently a larger outer moon does one orbit in the time it takes a smaller object within the rings to do two orbits. This means that once every two circuits, the inner object gets an extra gravitational kick. By going faster it moves to a different orbit, thus leaving a clear track within the rings.

Is everything we know about the universe wrong?

I missed this programme on Tuesday night so I'm watching it on the i-player. I know about dark matter and dark energy, but I've never heard about dark flow. I'm trying to learn something new about physics every day, so hopefully I'll know about dark flow by the end of the day.
http://www.bbc.co.uk/iplayer/episode/b00rgg31/Horizon_20092010_Is_Everything_We_Know_About_The_Universe_Wrong/

Brian Cox on BBC2 on Sunday night

If you missed the programme last night, you must see Prof Brian Cox on the wonders of the solar system:
http://www.bbc.co.uk/iplayer/episode/b00rf172/Wonders_of_the_Solar_System_Empire_of_the_Sun/

He covers a lot of stuff about the Sun and the Solar System. I love his enthusiasm. I am going to re-create Herschel's tin can experiment in the summer and I particularly admired the "That's why I love physics" aside at the end of that sequence in the programme.
If it doesn't make you want to become an astronomer, nothing will.

Mist in the valleys

Sorry there haven't been many posts recently. It's the busiest time of year! Still no sunspots, by the way. That's 5 months I've been watching.

At half term, I was up in the hills above Haweswater. There was a reasonably cloud base above our heads but mist kept forming in the valley below and then rising up past us. see photo.

Here's the physics explanation that I came to:

The slopes below us were south facing and catching the warm sun.

This made the snow melt and then evaporate.

The water vapour hit the cold valley air and condensed into mist.

This was warmed by the Sun so it expanded and became less dense, thus rising.