## Posts Tagged 'Physics'

### How Big was the Bomb?

By a brilliant application of dimensional analysis, G.I.Taylor estimated the explosive energy of the first atomic blast, the Trinity Test (see this week’s That’s Maths column in The Irish Times, TM053, or search for “thatsmaths” at irishtimes.com).

US army soldiers watching the first test of an atomic weapon, the Trinity Test.

### “Come See the Spinning Globe”

That’s Maths in The Irish Times this week (TM050, or Search for “thatsmaths” at irishtimes.com) is about how a simple pendulum can demonstrate the rotation of the Earth.

Reconstruction of Foucault’s demonstration. Original experiment in 1851. [Illustration (1902) from the cover of WIlliam Tobin’s book [1].]

Continue reading ‘“Come See the Spinning Globe”’

### Rollercoaster Loops

We all know the feeling when a car takes a corner too fast and we are thrown outward by the centrifugal force. This effect is deliberately exploited, and accentuated, in designing rollercoasters: rapid twists and turns, surges and plunges thrill the willing riders.

Many modern rollercoasters have vertical loops that take the trains through 360 degree turns with the riders upside-down at the apex. These loops are never circular, for reasons we will explain.
Continue reading ‘Rollercoaster Loops’

### White Holes in the Kitchen Sink

A tidal bore is a wall of water about a metre high travelling rapidly upstream as the tide floods in. It occurs where the tidal range is large and the estuary is funnel-shaped (see previous post on this blog). The nearest river to Ireland where bores can be regularly seen is the Severn, where favourable conditions for these hydraulic jumps occur a few times each year.

But you do not have to leave home to observe hydraulic jumps. Continue reading ‘White Holes in the Kitchen Sink’

### New Estimate of the Speed of Light

A team of German scientists have recently discovered a new method of measuring the speed of light using Einstein’s famous equation

E = m c2

### The Pitch Drop Experiment

Later this year a big black blob of sticky pitch will plummet from a funnel and plop into a beaker. The story is recounted in this week’s That’s Maths ( TM017 ) column in the Irish Times.

In one of the longest-running physics experiments, the slow-flowing pitch, under a bell-jar in the University of Queensland in Brisbane, will ultimately lose its battle with gravity …

### Packing & Stacking

In That’s Maths this week (TM004), we look at the problem of packing goods of fixed size and shape in the most efficient way. Packing problems, concerned with storing objects as densely as possible in a container, have a long history, and have broad applications in engineering and industry.

Johannes Kepler conjectured that the standard method used by grocers to pile oranges and gunners to stack cannon balls is the most efficient, but this conjecture was proved only recently by Thomas Hales. The mathematics involved in packing problems includes computational techniques, differential geometry and optimization algorithms.

The Foams and Complex Systems Group in Trinity College Dublin have recently discovered some new dense packings of spheres in cylindrical columns. An International Workshop on Packing Problems took place in TCD on 2-5 Sept. 2012. For more information, look here.