Archive for February 20, 2013

The Problem of the Dangling Magnet

Posted in Cute Problems with tags , , , , on February 20, 2013 by telescoper

Here’s a variation on a physics problem we discussed in my first-ever Skills in Physics Tutorial at the University of Sussex. I hadn’t realized that solutions were provided for Tutors so had to exercise my enfeebled brain in finding a solution. You’ll probably find it a lot easier…

A rectangular bar magnet hangs vertically from a pivot at one of its ends. When gently displaced the magnet undergoes small oscillations either side of the vertical with a period of one second.  A horizontal magnetic field is then applied so that the equilibrium orientation of the magnet is  45° to the vertical. If the magnet is gently displaced from this new position, what is the new period of oscillation?

Comment: you do not need any further information about the size, shape or mass of the magnet in order to solve this problem.


Black is the colour of my true love’s hair

Posted in Jazz with tags , , on February 20, 2013 by telescoper

Nina Simone. Emile Latimer. Live in 1969. Magical.

Stars and Planets

Posted in Poetry with tags , , on February 20, 2013 by telescoper

Trees are cages for them: water holds its breath
To balance them without smudging on its delicate meniscus.
Children watch them playing in their heavenly playground;
Men use them to lug ships across oceans, through firths.

They seem so twinkle-still, but they never cease
Inventing new spaces and huge explosions
And migrating in mathematical tribes over
The steppes of space at their outrageous ease.

It’s hard to think that the earth is one –
This poor sad bearer of wars and disasters
Rolls-Roycing round the sun with its load of gangsters,
Attended only by the loveless moon.

by Norman MacCaig (1910-1996).