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quinta-feira, 5 de setembro de 2013

Os Ímanes são estranhos... E Arduino Congelado(!), o Museu das Invenções estará a votos, e Papercraft Mecânico...

Os Ímanes são estranhos... Podem-se calcular as forças de atracção de dois Ímanes de Diâmetro igual, mas de Diâmetro diferente... Já é outra coisa!
Vejam este artigo  do Blogue da KJMagnetics, onde ainda podem encontrar um App para calcular forças de atracção de Ímanes de diâmetro igual, e um gráfico para diferentes.
E se quizerem ver como os Ímanes mais achatados têem uma atracção desigual, vejam este Vídeo:




Magnets Are Weird

In this article, we discuss a few things that might make you question what you think you know about magnets.  We’ll show magnets stronger at the edges than at the center.  We'll see magnets that won’t attract to center upon one another.  We’ll even make the north pole of one magnet stick to the north pole of another.
Mental Models of Magnets
The forces between magnets have long fascinated us.  It is a strange thing to think about: forces that you can’t see can cause things to move.  Albert Einstein described his first interest in science stemming from his fascination with a magnetic compass at a young age.
When we think of magnets, most of us think about how they work in terms of an analogy:  We might think of magnets as having invisible mechanical springs between them.  Or we follow simple rules that apply in most situations:  “Opposites attract” or “the north pole of one magnet attracts to the south pole of another” to predict their behavior.
In many cases, this way of thinking works pretty well.  In some situations, though, it completely fails to predict the actual behavior of magnets.  The “model” is too simplified, and doesn’t accurately describe how magnets behave.  Whenever we find magnets behaving in ways that don’t seem intuitive, we find ourselves muttering, “Magnets are weird!”


  




 

Dica do nosso amigo Alan Metcalfe, o Arduino agora foi congelado, para se conseguir mais velocidade dele, por isso, se são fâns do Overclocking, leiam isto:  
 
 

Overclocking Arduino UNO with liquid nitrogen

I must be missing the over-clocking gene, but a lot of modders love to push a piece of kit that bit further, sometimes by any means necessary.
That seems to be the case with a modder called Michail who has managed to overclock an Arduino using liquid nitrogen, no less. Cooling to -196°C he hits speeds of 65.3MHz.
Why overclock a dev board with liquid nitrogen? He answers this one in a blog post – because he could, and he wanted to learn how electronics behave at cryogenic temperatures. And he says he was just curious to see “how much juice you can squeeze out of AVR if you push hard enough”. (AVR is the “C” environment for programming Atmel chips.)






 




A partir do dia 16 de Setembro, podem votar na proposta 395, que já figura no Lisboa Participa, como um Projecto, e podem ir à página do Facebook, também:
  

projectos

Cultura
Museu da Criatividade e Invenção de Lisboa

Museu que aborda a aplicação da ciência com fins utilitários, comerciais ou industriais, i.e. as invenções, com um foco na inventividade e criatividade de origem portuguesa, dando a conhecer ao público em geral o que se tem feito e faz neste domínio e sendo também um espaço activo de fomento da criatividade, permitindo experiências hands-on que atraiam todo o tipo de público mas com um foco na camada infanto juvenil.
A definir
500000.00
18 meses
 
 
Vão já agora à página do Facebook, e carreguem em "Like"!

  









E Rob Ives volta a atacar, com esta maravilha mecânica, e em Paperctaft, por isso, sigam este Projecto, e boa sorte, Rob!


Using a Ratchet to Drive a Key

I'm working on a project for client that has a decorative clockwork key on its side. I'd really like key to turn as the model operates. The character itself will be jumping up and down so I'm trying to harness this motion to turn the key. If I can get the mechanism to work well it would apply well to a clockwork robot model like the one in the sketch below which I can then make into a model for robives.com.






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