thinking outside the tank

recumbent blackberry quantum zinc karma

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A few days ago I walked to the shops to buy a bag of lemons; that’s what you need to make lemon and courgette soup and then 2 kg of bramble jelly. On the way there I stopped to pick some blackberries which weighed in at just over a kilogram. This is not the best photograph ever taken of blackberries, but they are the blackberries I picked.

On the way home, I called in at the estate agent to pick up details of a 1-bedroom apartment in a Grade 2 Listed building which is shortly coming on to the market. It’s set in 8 acres of grounds and will have a security gate controlling access. This is the estate agent’s photograph and I hope the fact that I’m giving them free publicity – click on the photo for more details – will ease my way in the copyright infringement suit.

Manor House

I chatted for a while with the agent, then left and walked towards home. The road goes downhill and there’s a steep bank down to the right of the path which has a crash barrier at the top. Half way down this slope a car approached. When it was nearly up to me, the object shown below detached itself and carved a silhouetted parabola towards me. It flew past, dangerously close, and clattered into the barrier.

wheel balance weight

You may recognise this as a type of weight used for wheel balancing. I recognised it as a very lucky escape. If I had collected one fewer blackberry or exchanged one fewer pleasantry with the estate agent I would certainly have lost my balance as this thing struck me at x miles per hour.

That set me thinking in a number of directions. First, could I have made it in a freak show (those who know me would say ‘easily’) – roll up, roll up; see the man with the wheel balancing weight embedded in his skull.

Next, what was the value of x? In other words, how fast was the weight travelling towards me? I love this kind of problem. The diameter of the wheel was about 2 feet, so the circumference would be 2π or 6.28 feet. The wheel would make 5260/2π or about 837 revolutions per mile. At 30 miles per hour that’s (837*30)/3600 revolutions per second…then it occurred to me (duh!) – if the car was travelling at 30mph then the outer edge of the wheel must also be travelling at 30mph. The rim of the wheel had a diameter of about 20 inches, so the speed of the weight as it left the wheel was about (20/24)*30 or about 25mph. Which just goes to show there are better ways of killing a pig than choking it on π  (blackberry or otherwise).

How many of you budding Sherlocks out there have already identified the projectile from its distinguishing features? The markings on the weight are:

40 Zn 326 X

The 40 is its weight. I know that because I weighed it and it weighs 40grams. Zn means it’s made of zinc. 326, I think, identifies a style of wheel. X is an unknown to me. What is clear is that this particular weight didn’t have my name on it.

So, a lump of zinc went hurtling by my head with a momentum of 0.445kg-m/s. Was it luck or fate that I wasn’t a few more feet along the road? Was it randomness, or some kind of quantum zinc effect where all of the atoms in the weight experienced the probability that they would head off  at a tangent to the wheel?

If I were a Buddhist I might think it was karma. After all I did blog a while back about returning my car to the finance company and taking to my recumbent tricycle (Nil by ear). Was karma saving me with early payback in this lifetime for a virtuous act or was it a shot across the bows warning me what was to come?

What worried me more than anything, though, was that the driver of the car might not notice his loss until he reached a critical speed on the motorway when the vibrations would set in and maybe a considerably greater mass of metal would leave the road. It’s being so cheerful that keeps me going.

Copyright © Colin Hazlehurst 2010 (pace

Thanks to Frances Hazlehurst for copy editing.

Written by netkingcol

August 12, 2010 at 7:09 pm

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