Teeth Are Harder Than Steel

Hardness of various materials
Infographic created by Grok

Did you know that on a modified Mohs hardness scale that runs from 1 to 10, tooth enamel would rank at 5? That's harder than mild steel at 4.0 to 4.5 and softer than glass at 5.5.
Hardness (resistance to localised plastic deformation and scratching) is just one of several material properties, including strength (ability to withstand applied stress without failure), toughness (the ability to absorb energy before fracturing), ductility (the ability to be stretched) and malleability (the ability to undergo plastic deformation such as being beaten or rolled into shape).
The scale isn't a linear one, and is a qualitative, ordinal scale, meaning it only ranks minerals in order from softest to hardest without using uniform gaps between the numbers. So for instance, diamond at 10 is about four times harder than corundum at 9. Glass is about 25% harder than tooth enamel.
If a material is hard, it doesn't necessarily mean it's strong. Glass is harder than steel, but brittle and not tough. However, it's strong in compression, but not in tension.

Reduction in Rate of Water Level Decrease in Poulaphouca

Water level in the Poulaphouca Reservoir
Image courtesy ESB

The water level in the Poulaphouca Reservoir is still dropping, albeit at a slower weekly average than a month ago, when it was falling by about 2 cm to 2.5 cm per day.

Printer Frustration and Vodafone Broadband Goes Down

I resorted to dismantling my printer during the outage. Didn't have any success with that. Three blank cartridges — one filled with Quink ink (which worked successfully for over a year) and a brand new one wouldn't work.

Hard-to-Read Maps: Issues With Google Maps and OpenStreetMap

Tailte Éireann map

Whenever I'm out and about, it's nearly impossible to make out L roads on maps on my phone in bright sunlight because of the low contrast.

"Flood" on the River?

Flow versus time for Golden Falls dam
Image courtesy ESB hydro

Does anyone know whether the ESB are generating from the Golden Falls power station? Forecasted flow has been 3 m³/s for the last week or two. However actual flow is tabulated at 2 m³/s.

How Fast Is the Level Dropping in the Poulaphouca Reservoir?

Poulaphouca lakeside
© Eugene Brennan 

A question was asked on the Blessington Blog today to the effect, “Will the lake get as low as this again over the next weeks?” It showed a photo of the Poulaphouca Reservoir taken during a previous drought, in which neat linear piles of rocks could be seen along the shoreline, clearly marking the locations of the walls of houses that were submerged when the valley was flooded in the 1940s.

What Are Clicks?

Image made by Grok.

What's the difference between a click or thump sound (e.g. when you hit something with a stick or hammer a nail) compared to striking a bell or a string in a musical instrument? It's mainly due to the amount of damping involved.

How To View What's Behind Your Washer Drum

© Eugene Brennan

You can check what's between the inner and outer drums of a washing machine, or check for limescale build-up on the heating element, by spinning the drum and illuminating it with a bright torch.

Three Reasons the Summer is Warmer Than the Winter

Created with ChatGPT.

A common misconception is that the Earth is closer to the Sun in summer, but it's actually further away. Diagrams would be better for explaining this. I'll get around to it, but I'll try to do it with words for now. 

What Are Voltage Regulators Used For?

78XX series of voltage regulators. E.g. 7805 and 7812 having regulated outputs of plus 5 volts and plus 12 volts respectively. Silverxxx, CC BY SA 3.0 Unported via Wikimedia Commons.

We're surrounded by electronic gadgets and appliances, and even devices that don't appear to be electronic may use electronic circuitry internally. For electronics to work properly, it's imperative that voltage be stable and constant.

How to Measure Length, Distance and Area on Google Maps

Public domain image from Canva

The Google Maps measuring tool can be used to measure the distance between two points, and the result is displayed in feet and metres. Alternatively, values are displayed in miles and kilometres if a user zooms out to view a greater-sized region of the map.

Resistors in Series and Parallel: Formula Derivation and Examples

© Eugene Brennan

Formulas for Resistors in Series and Parallel

Resistors are ubiquitous components in electronic circuitry both in industrial and domestic consumer products. Often, in circuit analysis, we need to work out the values when two or more resistors are combined. In this tutorial, we'll work out the formulas for resistors connected in series and parallel.

The Cork-Dublin Transmission Pipeline and Gas Distribution to Kilcullen

Gas distribution network in central Kilcullen from the interactive Dial Before You Dig website. Image courtesy Gas Networks Ireland.

On 4th March last year, a press release was issued by Uisce Éireann to media and local public representatives to the effect that:

“Civil Engineers are carrying out pre-work activities on the 225mm pipeline, which involves a localised crossing over the High Transmisison (sic) Gas main under the supervision of Gas Networks.”

Immersion Heaters and Potential Fire Risks

Immersion heater terminal box. © Eugene Brennan

So I was doing some gardening for the sister today and she mentioned a smell that was coming from her immersion. This immediately rang alarm bells in my engineering head, knowing what was likely to have happened—So I investigated.

My Telemetry Software Didn't Control Voyager 1

Credit: NASA/JPL-Caltech

NASA's decision to switch off an instrument on Voyager 1 to keep the spacecraft operating reminded me of my much less glamorous work in a past life, when I wrote telemetry software to control pumps and other equipment in sewage and water treatment plants.

How Can Insects Survive Falling From a Height?

Forces on a falling insect. © Eugene Brennan

One of the reasons insects don't hurt themselves when they fall is because they have a low terminal velocity and are travelling relatively slowly when they reach the ground.

Learn How to Solder: A Complete Guide for Beginners

Image by permission Weller Tools

A Basic Skill When Building Electronic Circuits

Soldering is a fundamental skill essential to learn when building electronic circuits or fixing circuit boards.

Kippure TV Mast Visible From Kilcullen

Kippure in the Wicklow Mountains, photographed from Kilcullen. © Eugene Brennan

I took this with my 10-year-old Nikon D5300 SLR from St. Brigid's Well on Saturday evening. The second photo below is a crop of the 6000-pixel-wide image. If you have good eyesight, you can see the 127-metre-tall television transmission mast on Kippure on a clear day.

Why Is Most of an Iceberg Under Water? And How Much?

Original uncaptioned image Lurens, public domain image via Pixabay.com

Ninety Percent of an Iceberg Is Below the Waterline

Icebergs can be massive, but did you know that you're only seeing literally the tip of them above the water? Yes, up to 90% of an iceberg's volume can be under water. But why does that amount sink and not just float above sea level like the rest of it? In this article we explore why.

What's the Difference Between Analogue and Digital?

© Eugene Brennan

Analogue vs. Digital

We often hear about analogue and digital in the context of communications, sound recording, cameras, TV, radio, and electronic devices. But what exactly is the difference, and is digital better than analogue? Why has digital replaced analogue in audio, digital imaging, and electronic communication?