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. Terminal velocity is the maximum velocity attained by a falling body in a fluid such as air or water and subject to a force called drag, (resistance to motion). For humans, it's around 120 mph or 54 m/s lying flat. For an insect, it's typically around 2 m/s. Once the increasing drag force balances the weight (another force), there's no net force and an object stops accelerating (Newton's second law of motion). Also when an insect hits the ground, because it has such a small mass, the g-force on its body is small because it has to shed so little momentum, and that also helps prevents damage. So it's a combination of low terminal velocity, small mass and also having an outer protective layer or exoskeleton that gives them protection.

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. It's approximately 7 m taller than the Spire in O'Connell Street in Dublin and located 17.5 miles away from Kilcullen as the crow flies. (I can just about make it out with the naked eye). At night of course it's very noticeable, and the beacons on the mast can be seen flashing in the distance. They used to be red, but they changed them to white at some stage. I've seen the flashing from as far away as Kilmeague.

I haven't figured out why this camera always takes such dull photos. I reckon smartphones must boost the colour saturation, highlights and contrast in images to make them more vivid. I have the setting for this (can't remember what it's called) set as "neutral" in the camera so that images aren't altered. I can always change the settings later during post processing.

Edit: An FB photography group I'm a member of confirms that this is the case and images are flat if neutral photo style is selected. Saving photos as JPGs compresses images and reduces filesize, so I'm going to retake the photo and save as raw to see whether it makes much of a difference as regards detail and artefacts.

The TV mast on Kippure (a crop from the image above) © Eugene Brennan

 

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?

Vodafone Internet Service Down After Thunderstorm

 

The Internet was dropping intermittently since the thunderstorm the other night. A Vodafone technician replaced the modem yesterday afternoon, but still no go. Then the service disappeared completely when the technician was still working on it.

Why Is Binary Used in Electronics and Computers?

Why is binary used in electronics? Geralt via Pixabay.com

Why Do Computers Use Binary?

The binary numbering system is the basis for the storage, transfer and manipulation of data in computer systems and digital electronic devices. This system uses base 2 rather than base 10, which is what we are familiar with for counting in everyday life.

How to Convert Decimal to Binary and Binary to Decimal

Binary number and its decimal equivalent. © Eugene Brennan

Base 2, the Basis for Binary Code

The base 2, or binary numbering system is the basis for all binary code and data storage in computing systems and electronic devices. This guide shows you how to convert from binary to decimal and decimal to binary.

How to Convert Hex to Binary and Binary to Hexadecimal

© Eugene Brennan

The Hexadecimal Numbering System

The base 16, also known as hexadecimal (abbreviated to hex) numbering system is regularly used in computer coding for conveniently representing a byte or word of data. This guide shows you how to convert from hex to binary and binary to hexadecimal.

The Andromeda Galaxy: "It's Big, And Also Faaarrr Away"

The apparent size of the Andromeda Galaxy, compared to that of the Moon. AI image created by Grok.

At a distance of 2.5 million light-years, or 24 million trillion km, the Andromeda Galaxy is the most distant object visible to the naked eye. We can see it because space is mostly empty, and light from the stellar object reaches us relatively unchanged, unlike what happens when we view distant objects on the horizon on Earth.

Loading Data for the Kilcullen 38 kV Substation.

Loading data for the Kilcullen 38 kV Substation, courtesy ESB Networks.

From the ESB Networks document 38 kV & 110 kV Station Special Load Readings. 

The table shows summer and winter loads in megawatt (MW) for transformers T41, T42 and T424.

It Came From Outer Space....

Nostoc commune (Latin name), also known as "jelly fungus". © Eugene Brennan

 Well not quite. This is probably Nostoc commune (Latin name), also known as "jelly fungus", "star jelly" or "witch's butter". It's not actually a fungus, but a colony of bacteria. There's loads of it in a patch on my yard, but it sometimes grows on lawns. It's extremely slippery on a lawn. Apparently it's eaten as a salad in the Philippines when dried out. I'm a fussy eater so I won't be trying it anytime soon.

More information on jelly fungus here on Wikipedia.

Off-Road Lanes for Cycling in Kildare and Wicklow

Lane from Barretstown to Bishopshill Commons. © Eugene Brennan

I'm always on the lookout for new trails and farm lanes for cycling on. Some are marked with a cul-de-sac sign, and just end up at farmhouses. However, others actually link two roads. Usually, there’s no sign at the junction where they meet a main road, or even a road number, so it can be a mystery where they go.

Available Substation Capacity in Ireland

Information on substations. Image courtesy ESB Networks.

This interesting interactive map on the ESB Networks website shows transformer capacities. A "substation" indicated on the map could be an actual town substation like the one at Sunnyhill, with 1, 2 or more transformers and associated switchgear and circuit breakers, or a transformer in a cabinet or small building (common in the newer housing estates).

What Is the Ground Wire For?

© Eugene Brennan

What Is a Ground Wire?

The hot and neutral cores in a power cable are used to supply current to the appliances in your home. So what about the green wire? Why is it needed? This is known as the "ground" and is an additional wire that is included for the safety of you and your home.

Re-Discovering the Mill Stream Arch

One mill is marked on the OSI c.1837 first-edition six-inch map. Image courtesy the National Library of Scotland, licence CC-BY.

I hadn't seen it since around 1982 or '83. I thought it was covered with scrub and brambles over the decades, but not so. This is a good time of the year to investigate it before the brambles get going. My theory is that it could have been the opening to a culvert/mill race that diverted water to a second mill in the adjoining field beside the cemetery car park or it may have been the return feed to the stream. One mill is marked on the 6-inch, first-edition OSI map and was located just over the wall from where the bins used to be kept in the cemetery. The ruin is still there. There's an arched culvert under the Mile Mill road, south of the lodge, that fed water to this mill.
I think the arched opening into the stream is unlikely to be a latrine outlet or drain as it's too wide. I thought most of the arch was submerged below the waterline, but possibly the bed of the stream has dropped over the last four decades due to erosion. Anyway, I didn't have a camera with me. That's a shame because the arch was nicely lit up by the setting sun.
Will investigate further tomorrow and take some photos.

The map above is a ChatGPT-sharpened version of a screenshot of the c. 1837 first-edition six-inch map available on the National Library of Scotland website. The scans appear to be a bit clearer than those available on Tailte Éireann's Irish Townland and Historical Map viewer.
Map reproduction licence CC-BY, courtesy the National Library of Scotland.

YouTube Requirements and Broadband Speed

Connection speed required for YouTube. Image from Google Help

Unless you have lots of people in your home feeding off  your Internet service and sharing the bandwidth, ultra-high-speed connection promotions such as "Gigabit broadband" are just marketing hype. The table above shows the recommended connection speeds from Google for streaming video from YouTube. Vodafone keeps trying to sell me such a service using a fibre-optic connection that replaces copper wires to the cabinet and which would increase my speed from 100 Mbps to 1 Gbps, but I'm stubbornly refusing as the current speed is perfectly adequate. A faster connection probably increases upload speed (which I think is normally about one tenth of download speed), but most people aren't in a hurry when uploading, unless they can't wait to backup thousands of photos or put their latest video online. Eventually I'll have to give in, because copper lines, which Vodafone rent from Eir, will ultimately be replaced. The process is slow, because there are legacy systems that still require them. 
I ring Vodafone every year, three months before my contract is due for renewal and negotiate a loyalty discount, getting a six-month discount. It's only €5 per month for 6 months, but better than nothing.

A Child Can Push Harder Than a Lawn Mower Blade

AI image generated by Google Gemini.

Did you know that a child can probably produce more torque using their arm, than a lawn mower engine can generate to turn the blade? Surprisingly, the figure for the torque of a 5 hp engine used on a mower is 7 to 10 foot-pounds (ft·lbf) in the imperial system or 11.5 to 13.6 newton-meters (Nm). Applied torque is simply force multiplied by distance, so 1 pound-force applied over a distance of 1 foot from a pivot is 1 foot-pound. In the metric system, the unit of torque is the newton-metre (Nm). A torque of 1 Nm is equivalent to one newton—the SI unit of force—applied over a distance of one metre. The speed of a lawn mower blade is more important than torque, and blades are driven directly by the crankshaft without reduction or overdrive gearing. Blades typically spin at the engine speed of around 3000 RPM, giving a blade tip speed of around 200 mph, or 90 metres per second.

As we saw in the article Interesting Facts - What is Torque?

power = torque x angular rotation speed

So while a child may be able to exert more torque with their arm than a mower engine can exert on a blade, they wouldn't be able to match its power. Another piece of the jigsaw is that the quoted figure of 11 to 13 Nm is for the drive torque from the engine. Since a blade is spinning at around 3000 RPM, it has a lot of inertia. The technical term for this when a rotating body such as a flywheel or blade is involved is moment of inertia. When a blade slows down as it impacts grass, the change in angular momentum creates a force, just like the way a car or any linearly-moving object creates a force as it slows down due to friction, or when it hits something (think of the huge force produced by a hammer, typically many tonnes, when it hits a nail). So the force produced by a blade as it impacts and shears grass is much greater than the force that the engine itself could have generated.

Note: You may be wondering why "newton" in "newton-metres" above isn't capitalised.  The unit is named after the English scientist Isaac Newton. It's not a typo. In the International System of Units (SI), or Système international d'unités, units named after a person are not capitalised. However, the symbol is, N in this case, Units are normally lower case, as are prefixes. However, prefixes over one million are capitalised—so kilometres is km, but gigahertz is GHz.

Cantilevered Boardwalks For Motorway Bridges?

Bridge over M9 Kilcullen Bypass on Sunnyhill Road. Image courtesy Google.

When Kildare County Council, or whoever was responsible, produced the spec for this bridge, (and the one over the M7 at the Bundle of Sticks Roundabout outside Naas), they left out foothpaths. Maybe it was lack of common sense and an attitude of "Sure, only cars go out there". Or perhaps it was due to penny pinching and lack of foresight and a narrow bridge was cheaper than one a couple of metres wider? Anyway, I'm wondering could boardwalks/cantilevered foothpaths be fixed onto the sides, exterior to the parapets?
It would obviously be impractical to install foothpaths on the inside of the parapets due to to both lanes being reduced in width. As it is, cars can't pass pedestrians safely without partially moving into the other lane. An article by Paul MacDonald, Kildare National Roads Office, on the construction of the M7 Newbridge Bypass and M9 Kilcullen Bypass is available on the Kilcullen Diary here.

The section about the earthing of the steelwork of the underbridge for the River Liffey is interesting—High voltage pylons can induce voltages and currents in conductors, potentially leading to different and hazardous potentials between isolated elements of a structure. Bonding them together eliminates these voltages and earthing a structure pulls the voltage down to ground (similar to the equipotential bonding in bathrooms, where metal objects such as drains, radiators, towel rails, water pipes and metal baths are bonded together):

Bridge over M9 Kilcullen Bypass on Sunnyhill Road. Image coiurtesy Google.

How to Calculate Bolt Circle Diameter (BCD) for Chainrings and Bash Guards

Bolt circle diameter (BCD). © Eugene Brennan

What Is a Bolt Circle Diameter (BCD) or Pitch Circle Diameter (PCD)?

As you may be aware, if you've found this guide, a bolt circle is an imaginary circle that passes through the centre of the bolt or screw holes in a round pattern. This is typically a wheel hub on a vehicle, chainring on a bicycle or flange on a pipe. The diameter of this circle is known as the bolt circle diameter (BCD) or pitch circle diameter (PCD).

Typically, BCD is quoted for chainrings on bikes and the bash guards that cover them, and you can calculate it by measuring the distance between the mounting holes of the chainring on the spider. If you need to order a part for a bicycle or check the BCD of a flange and can only measure the bolt hole spacing, you need to know the formula for working it out. Alternatively you can skip to the end of this guide where there are tables for various bolt spacings.