Monthly Archives: November 2009

Estimating density

It turns out that estim­ating density is some­thing that pupils find really hard. I asked a class of pupils to estimate the density of four sub­stances: air, water, mercury and wax. Before you read any further, try to estimate (in … Continue reading

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Space Tourists

Since 2001 seven people have become space tourists. Dennis Tito, a US entre­preneur, was the first space tourist, in 2001. He was followed by South African entre­preneur and Ubuntu Linux creator Mark Shut­tle­worth in 2002. Shut­tle­worth was followed by Gregory Olsen, … Continue reading

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First Collisions

w00t!

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Whiteboard

You know you’ve had a good lesson if the white­board looks like this after the lesson.

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Getting rid of data

I had to get rid of an old, partially-functional, memory stick. Deleting all the data, format­ting the drive and over­writing the free space is a good start, but any sensible user knows that data is never really gone. The best … Continue reading

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More slow motion lightning

Fol­lowing on from this post about slow motion light­ning I found a longer video with more strikes, shot from an aircraft. [youtube]http://www.youtube.com/watch?v=Nh15VjGkK5Y[/youtube] More amazing videos and pho­to­graphs at ztresearch.com.

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MPG v L/100km

MPG Miles per gallon (MPG) is a mis­leading quantity. Miles per gallon is often referred to as a meas­ure­ment of fuel con­sump­tion but it isn’t. Miles per gallon is a measure of the car’s fuel effi­ciency: how many miles the … Continue reading

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Baseball bat and centre of mass

How is this possible? [youtube]http://www.youtube.com/watch?v=YngyMco72QA[/youtube] It’s possible because the baseball bat pivots around its centre of mass, but the centre of mass con­tinues to move in a straight line.

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