Press Release From the ESB About Potential Releases From the Poulaphouca Reservoir

Poulaphouca Lake. © Eugene Brennan

Water isn't released directly into the River Liffey south of Ballymore Eustace from the Poulaphouca reservoir — it's discharged indirectly from the Poulaphouca dam into a compensatory lake in Ballymore. This acts as a buffer, protecting the river from huge surges and flooding. Although it's not related to surges on the river, a surge tank adjacent to the Liffey bridge over the gorge on the N81 protects the pipes, or penstocks, that deliver water to the turbines in the generating house from hydraulic shock.

Devils Tower, the Hill of Allen, the Valley Park and Close Encounters of the Third Kind

Devil's Tower in Wyoming. Ben Stephenson from Cleveland, OH, CC BY 2.0 , via Wikimedia Commons

If you were watching Close Encounters of the Third Kind this afternoon (I hadn't seen it for maybe 15 years), you would have seen the towering rock formation that's used as a plot device and features in the end of the movie when the huge spaceship appears and the aliens emerge. This is Devils Tower in Wyoming, classed as a butte and possibly a laccolithic formation, composed of igneous rock. A butte is an isolated hill with steep, often vertical sides and a flat top. Igneous rock began as molten rock or magma that originated from inside the Earth, and then cooled.

Top 100 Cool Science Facts for Kids!

Photo courtesy Geralt on Pixabay. Text overlay © Eugene Brennan

Why is the sky blue? What is air made of? How many stars are there?
World of wonder fun science facts that every child should know! This article covers space, nature, technology, engineering, elementary mathematica, chemistry, physics and biology.
Science is fascinating and tries to explain how everything in the world and outer space works. Science gives us the answers to questions like "What is electricity?" and "How does an aeroplane fly?" Read on and learn 100 more cool science facts! 

Super Human Strength and an Injury on Church Mountain

Fence on Church Mountain, Co. Wicklow. © Eugene Brennan

In 2019 I was making my way down a gully on Church Mountain near Hollywood with my bike slung over my shoulder. I had cycled half-way up on the trails at the back of the mountain and was going to go further, but it was getting late in the day and I decided it would be wise to head home before it got dark. The gully was peppered with lots of rocks, covered in wet, slippery moss and algae and difficult to navigate. I was distracted by an annoying off-lead dog belonging to walkers behind me which kept barking at me. I lost my concentration, slipped and started to fall backwards, my bike pulling me down (which is why it's never a good idea to carry a ladder over your shoulder on a stairs).

Terminal Velocity of a Human, Free Fall and Drag Force

© Eugene Brennan

We all know that when an object is released from a certain height, it starts to fall. This, of course, is due to gravity, or more specifically the gravitational force of attraction between the object and the Earth. The force of gravity causes the object to accelerate and increase in velocity as it falls downwards towards the Earth. In actuality, both the Earth and the object are mutually attracted to each other, and the Earth moves upwards at the same time. However, since it's so massive in comparison to a small object and the force is so small, its movement is minuscule. 

How to Calculate the Sides and Angles of Triangles Using Pythagoras' Theorem, Sine and Cosine Rule

In this tutorial, we'll first learn the absolute basics about triangles. Then we'll learn about trigonometry which is a branch of mathematics that covers the relationship between the sides and angles of triangles.

What's Covered in the Tutorial?

• Polygons and the Definition of a Triangle
• The Basic Facts About Triangles
• The Triangle Inequality Theorem
• Different Types of Triangles
• Using the Greek Alphabet for Equations
• Sine, Cosine and Tangent
• Pythagoras's Theorem
• The Sine and Cosine Rules
• How to Work Out the Sides and Angles of a Triangle
• Measuring Angles
• How to Calculate the Area of a Triangle

Printer Ink Experiment

Printout using Quink fountain pen ink. © Eugene Brennan

I'm fed up buying inkjet cartridges for my Lexmark printer, which usually dry up and stop working. I was speaking to a technician about this and he said that the advice from manufacturers is that inkjet printers really need to be "exercised" every week or two by printing a couple of pages to prevent this happening. I predicted this in the 90s when I bought my first inkjet printer, having owned a fountain pen and knowing that the nib occasionally dried up. The print nozzles in inkjet printer heads are only a few tens of microns in diameter, so it's not unexpected.

A Book of Sketches by Stephen Leacock: A, B and C, the Human Element in Mathematics

From the Project Gutenberg

This was the final chapter in a book called Literary Lapses, written in 1910 by the author Stephen Leacock. It was one of the short stories included in the Exploring English anthology, one of the three books we studied for the Intermediate Certificate. The other two books were devoted to prose and poetry.
In the story, Stephen humorously personifies A, B and C as they negotiate the algebra problems encountered in maths problems.
The book is in the public domain and copyright has elapsed, hence the reason I have copied a portion.

Simple Machines: How Does a Lever Work?

© Eugene Brennan

What Is a Lever?

A lever is a simple device that works by changing the input force needed to do work and move something. Some levers do this by magnifying the force applied to them. In this tutorial, we'll explore how levers are used in our everyday lives and then learn the simple physics of how they work.

Examples of levers. © Eugene Brennan

The Lever: One of the Six Classical Simple Machines

The lever is one of the six simple machines which were defined by Renaissance scientists hundreds of years ago.

Another Faulty LED Street Lamp

From the DeadSure app for reporting faulty street lighting.

Too early to make a judgement, but something tells me these new LED street lights are less reliable than the older sodium ones. Which makes sense, considering sodium lamps are simpler and purely electrical/electromechanical, whereas LED lamps have more working parts— not moving parts, but semiconductors—that can fail. I reported this one that I noticed tonight because the upper path in the Valley Park seemed dark. There may be a couple more not lighting, further out the road closer to St. Brigid's Well.

LED lighting theoretically has a lifespan in the tens of thousands of hours (30,000 to 40,000 hours). However, in reality it can be less than this because the driver electronics fails.

57 Modes and Nothing Wrong

Bicycle rear light. © Eugene Brennan

Mystery light.

I've bashed it almost to the point of cracking the lens, put it in the freezer for half an hour while turned on and left a strong magnet in its vicinity and it still won't turn off. Yet when I'm cycling, after 100 m or so, it manages to turn itself off. And that keeps happening. The only thing I can think of is that deceleration in a certain direction is bending a spring in a clicky button. Or maybe it's condensation on the PCB. Or possibly constant vibration rather than large shocks.

Anyway, I hate the way they don't put proper switches on these things instead of buttons for changing modes that inevitably cause them to switch off on bad roads. It's difficult to get a decent backlight anywhere. I've tried eBay, Amazon and AliExpress.

 

Archimedes' Principle, Buoyancy Experiments and Flotation Force

Archimedes' principle. © Eugene Brennan

What is Buoyancy?

We've all experienced buoyancy. If you throw a football into water, it floats on the surface. In a swimming pool, you can float on your back and large ships float in the sea. Even things that sink such as stones, experience a buoyant force, but the force is insufficient to keep them afloat. Buoyancy is a force that pushes up on the underside of an object that's placed in a fluid. The fluid doesn't have to be water, it can be a gas such as air and helium balloons experience buoyancy, causing them to rise upwards.