A very interesting thread unfolded by ThreadreaderApp (via [Archive.is] Andrea on Twitter: “Interesting read!… “) starts at [Archive.is] Peter Kolchinsky on Twitter: “While not technically alive, there’s an evil genius to viruses that never ceases to amaze me. It’s one reason I became a virologist. A recent Nature paper reveal a remarkable trick SARS-Cov-2 learned that makes it nastier than the first SARS. Both viruses…”:
Archive for the ‘science’ Category
Why the current Coronavirus (SARS-Cov-2) is so much nastier than the first SARS
Posted by jpluimers on 2020/04/06
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100 km – how much needs to go into a tank? well2wheels/well to wheels (kWh).png at master · htc1977/well2wheels · GitHub
Posted by jpluimers on 2020/02/17
A big picture is below the fold.
Other graphical file formats at [WayBack] GitHub – htc1977/well2wheels: graphical WELL-TO-WHEELS Report Version 4.1 European Commission, 2014
via:
- [WayBack] 🄲🄷🅁🄸🅂🅃🄸🄰🄽 on Twitter: “Es gibt jetzt auch eine Version in kWh, anstatt MJ als Einheit für die Energie.… “
- [WayBack] 🄲🄷🅁🄸🅂🅃🄸🄰🄽 on Twitteri: “Inspiriert von @Elektro_Robin|s Foto aus dem Deutsches Museum München, Sonderausstellung Erneuerbare Energien über den tatsächlichen Energiebedarf verschiedener Antriebe, habe ich die Grafik neu aufbereitet und stelle sie hier allgemein zur freien Verfügung.… https://t.co/llBc0gVXGJ”
- [WayBack] Wieviel Energie pro 100 km? https://twitter.com/cfrey1977/status/1053239774176333825 – Kristian Köhntopp – Google+
- [WayBack] report_2014/wtt_report_v4a.pdf
- [WayBack] WELL-TO-WHEELS Report version 4.a : JEC WELL-TO-WHEELS ANALYSIS – European Commission
- [WayBack] Well-to-Wheels Analyses – European Commission
–jeroen
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Richard P Feynman – FUN TO IMAGINE (full)
Posted by jpluimers on 2020/01/24
On my watch list: Richard P Feynman – FUN TO IMAGINE (full) – YouTube
The first 5 minutes are already so great and full of imagination, that I need to find time to watch it once more after already watching it 2 times in full with some time in-between to reflect.
Via: [WayBack] Richard P Feynman – FUN TO IMAGINE (full) – DoorToDoorGeek “Stephen McLaughlin” – Google+
–jeroen
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Reminder to politicians: concrete blocks do not help against trucks
Posted by jpluimers on 2019/10/18
These physics lessens at school were useful after all.
TL;DR:
A concrete block of ~1.500kg will loose against a truck of ~9.000kg, especially if that drives 50 km/hour.
It will not stop the truck, but will start moving by itself in unexpected directions and speeds becoming a projectile by itself or worse: usually pieces break off traveling at quite high speed.
The video below shows what happens.
Beton blocks
Over the last year or so, concrete blocks are deployed in many places of the public areas. The usual deeper motivation is to protect against traffic.
The blocks are put on the ground without anchoring for a variety of motivations like flexibility, ease of deployment/removal, cost of blocks (EUR ~100 each) versus anchoring (EUR ~250 per block) in a non-interconnected way.
Often, the rectangular lego-like blocks with 8 bumps are used which come in two varieties: 40cm high (easier to sit on, look more friendly) of a mere 1200kg or 80cm high (look more massive) of only 2400kg.
Other concrete blocks used are roughly the same dimensions, so an average weight of ~1500kg is reasonable.
Trucks
An average truck (at about 10.000 kg) isn’t a static object. In cities they are usually allowed to drive at 50 km/hour, but during assassination attempts they drove much faster and also were much heavier.
Let’s assume however that a truck used is less heavy (not all bad people are smart to get a really heavy truck) at ~9.000kg.
Truck concrete collision
The assumptions so far: a truck of 9.000kg at 50 km/hour against a concrete block of 1.500kg at standstill.
Even though a collision with a truck looses some energy, a moving truck has a lot of it. So most of the energy from the truck will be partially or fully transferred via its momentum to the concrete block(s).
The physics involved here are about momentum:
- momentum = mass * velocity
- momentum in a system is conserved
Before colliding, the truck has momentum, but the concrete block does not. After the collision, the momentum is divided over truck and concrete block so they both have a velocity.
A few cases that can happen, usually in a combined fashion:
- The truck comes to a full stop and all momentum is transferred to the block. The block now travels 9.000/1.500 * 50 km/h which is 200 km/h if it was in front of the truck.
- If the concrete wasn’t fully in front of the truck, the truck will move in another direction as well as the concrete block. Those directions are hard to predict for the public.
- Part of the concrete comes off during collision. Since their weight is smaller, their speed will be higher (because momentum is conserved) and direction even less predictable.
–jeroen
References
- lego like concrete blocks: [WayBack] Duo Interlocking Precast Concrete Blocks for Temporary works and Cofferdams / [WayBack] stapelbetonblokken / [WayBack] megablokken
- trucks: [WayBack] Truck classification – Europe
- [WayBack] Momentum
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But what is the Fourier Transform? A visual introduction. – YouTube
Posted by jpluimers on 2019/10/07
[WayBack] If only math was taught like that when I was studying… – Adrian Marius Popa – Google+
–jeroen
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Handy interactive map of the periodic system – elements.wlonk.com
Posted by jpluimers on 2019/05/20
Handy interactive map of the periodic system: [WayBack] elements.wlonk.com
via: [WayBack] Interactive Periodic Table.Wonderful. Identify the typical uses for each element as you scroll over it.http://elements.wlonk.com/ElementsTable.htm – Lars Fosdal – Google+
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Thread by @MaxFagin: “November is here, and that means a massive shift is coming. And by “massive” I am of course referring to the redefinition of the kilogram unit of mass […]”
Posted by jpluimers on 2018/11/02
Good read: Thread by @MaxFagin: “November is here, and that means a massive shift is coming. And by “massive” I am of course referring to the redefinitilogram unit of mass that the world has been building up to for more than 100 years. Let me explain: 1/ I’ve h […]” [WayBack]
via: [WayBack] Das Urkilogrann wird arbeitslos. Es wird durch eine Definition ersetzt, die auf physikalischen Effekten statt auf einem Sample basiert. – Kristian Köhntopp – Google+
–jeroen
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Euler’s identity – cool explanatory videos by Burkard Polster
Posted by jpluimers on 2018/10/19
[WayBack] e^iπ = -1 – Daniela Osterhagen – Google+ reminded me of [WayBack] Euler’s identity (often called the most beautiful formula in the world) and these two great videos by Burkard Polster I bumped into a few years back below.
She points to a German link about “the most beautiful formula in the world”, to which I fully agree:
Gerade einmal sechs Symbole braucht es dafür
[WayBack] Freistetters Formelwelt: Die schönste Formel der Welt – Spektrum der Wissenschaft
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Spelling with element symbols from the Periodic table
Posted by jpluimers on 2018/09/11
The [WayBack] Periodic table – Wikipedia contains many symbols.
Combing them allows you to spell word. Not all words, but many of them can be spelled.
So I was glad finding the below article that started with the same fascination I had in chemistry class.
It has a great explanation of the algorithm, references to computer science literature and a nice Python implementation.
via: [WayBack] One of the best programming articles I’ve read in a while – This is why I Code – Google+
–jeroen
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TwistedDoodles • The truth about Eureka. (I say bollocks… A lot!)
Posted by jpluimers on 2018/08/30
I bumped into this a while ago, but since I’ve been doing quite a bit of research lately, it’s worth repeating.
–jeroen
Source: TwistedDoodles • The truth about Eureka. (I say bollocks… A lot!)
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The Wiert Corner - irregular stream of stuff 