ChemCrafter Les fluides non newtoniens Les fluides non newtoniens Les fluides non newtoniens sont des substances aux propriétés physiques et chimiques étonnantes. Sous l’apparence de fluides presque aussi liquides que l'eau, ce type de fluide a la particularité de devenir solide quand on y exerce une pression suffisamment forte. Partager De quoi s’agit-il ? En chimie, les fluides sont des milieux parfaitement déformables qui peuvent être gazeux (fluides compressibles), liquides (fluides peu compressibles) ou bien ni l’un ni l’autre (dans certaines conditions de température et de pression). La mécanique des fluides est la branche de la physique qui étudie le comportement des fluides lorsqu’on les soumet à des forces ou des contraintes. On distingue deux grandes familles de fluides en fonction de leur viscosité : les fluides dits "newtoniens" et les fluides "non newtoniens". Les différents types de fluides Exemples de fluides non newtoniens Recherches et applications Vidéo : Auteur : Audrey | Date de création : 23/08/2007
Make Your Own Co2 Fire Extinguiser Materials: - Candle- Wire Coat Hanger- Two 1 liter plastic soda bottles- Matches- Baking soda- Vinegar- Pliers and Scissors- Adult Supervision Watch the Co2 Fire Extinguisher Video Process For Making Your Own Co2 Fire Extinguisher 1) Use the scissors to cut off the tops of the plastic bottles. 2) Bend the coat hanger wire in a creative way to make a candle holder. 3) Light the candle and lower it into a soda bottle to prove it will not go out by itself when lowered into one of the plastic bottles. 4) Add three ounces of vinegar to one of the plastic bottles. 5) Once the bubbling has stopped. 6) Now this is the cool part. 7) Light the candle again and lower it into the container in which first held the Carbon Dioxide gas (the one you mixed the vinegar and baking soda in, then poured out into the other). 8) Now lower the lit candle into the container in which you poured the Carbon Dioxide gas into. The Science Behind the Co2 Fire ExtinguisherA fire requires oxygen, fuel, and heat to burn.
California Trees Nailed As The Source Of Mystery Infections The Canary Island pine is one tree species that hosts a fungus that causes disease in humans. Shamanic Shift Center/UC Davis/Wikimedia hide caption itoggle caption Shamanic Shift Center/UC Davis/Wikimedia The Canary Island pine is one tree species that hosts a fungus that causes disease in humans. Shamanic Shift Center/UC Davis/Wikimedia A false-color electron microscope image of the fungus Cryptococcus gatii, which can cause fatal illnesses in humans. itoggle caption Microbial Pathogenesis/Duke University A false-color electron microscope image of the fungus Cryptococcus gatii, which can cause fatal illnesses in humans. Microbial Pathogenesis/Duke University A fungus called Cryptococcus gattii can cause life-threatening infections, especially in people with compromised immune systems. But though people in Southern California have been getting sick from C. gatti for years, nobody knew how. Eucalyptus trees were a prime suspect, since they harbor the fungus in Australia. Bingo! Indeed.
How To Make Easy Slime Bat Sensory Play | Little Bins for Little Hands Quick And Simple Recipe For Making Bat Slime Hands-On Activities For Play And Learning Love all the great science and sensory play options for Fall and Halloween. What Is Slime? Is it a liquid or a solid? Materials Used: borax (laundry soap) Elmer's clear washable school glue 5oz water bat confetti or table scatter 2 bowls, spoons, cookie cutters (optional) cookie sheet (we use the dollar store variety for projects!) Easy Slime Bat Sensory Play My son can be a bit weary of new textures. Observe, explore and discover! Make a ball and watch it bounce! Use cookie cutters to cut out shapes and watch them melt away! How long will the slime flow until it breaks? Quick and simple, not to0, messy, science sensory play any day! Dollar Store Halloween Slime Please follow along with us Pinterest, Facebook, G+, or SUBSCRIBE to us by email on our side bar More Fun Science Play Ideas More Fun Playful Preschool Learning Activities #playfulpreschool (click on each photo for full article) Like this: Like Loading...
Hot water freezes faster than cold - and now we know why. Hot water seems to freeze faster than cold water, known as the Mpemba effect. The effect was named after the Tanzanian student who in 1963 noticed that hot ice cream mix freezes faster than a cold one. The effect was first observed by Aristotle in the 4th century BC, then later Francis Bacon and René Descartes. Mpemba published a paper on his findings in 1969. Theories for the Mpemba effect have included: faster evaporation of hot water, therefore reducing the volume left to freeze; formation of a frost layer on cold water, insulating it; and different concentrations of solutes such as carbon dioxide, which is driven off when the water is heated. Now a team of physicists from the Nanyang Technological University in Singapore, led by Xi Zhang, have found evidence that it is the chemical bonds that hold water together that provide the effect. The team now suggest it is these bonds that cause the Mpemba effect.
Unwrapping the chemistry of Christmas - Dr Mark Lorch, University of Hull How many chemicals do you think your body interacts with at Christmas? Loads! They’re everywhere, in the Christmas jumpers you’re wearing, the wrapping paper you’ve ripped to shreds and even in the preservative on your Christmas tree that stops the needles falling off. Chris - You mentioned that you were joining us earlier and you've been vigorously peeling an orange, but not for personal consumption I hope, not in the chemistry laboratory. Mark - No, of course not. Chris - Flame for the Christmas table? Mark - Yeah. Chris - So, we have one of my beautiful crystal candlesticks here and there is a candle sticking at the top of it and you have peeled the peel off of a very large orange and you bent the peel over. Mark - Exactly and watch this. Chris - Woh! Mark - Isn't that fabulous? Chris - That was about a foot high. Mark - That was a really good jet of flame there. Chris - Is that a trick stunt orange or is this for real? Mark - No, this is just a normal navel orange. Mark - So, I believe.
Catching oil in a net with nanotechnology | Ongoing chatter from a materials girl wondering about what matters Metal mesh with oleophobic coating keeps oil on top while water passes through. (Image source) Catching liquid in a net may seem like a crazy idea, but by adding a fine dusting of silica nanoparticles to a metal mesh, researchers have been able to create a new type of net. Hydrophobic surfaces (surfaces which repel liquid) are not new and several sprays can now be bought in your local hardware store, but researchers at Ohio State University added a extra ingredient, by topping the silica with a layer of fluorosurfactant to make the mesh oleophobic (surfaces which repel oil). Superoleophobic surfaces work by having a fluorinated component which provides low surface tension and a roughness component which prevents the solid and liquid from wetting and the super part just means that the liquid balls up with a wetting angle of more than 155˚. Metal coated with silica and fluorosurfactant can separate water from oil. Like this: Like Loading...
Candle Science Magic Trick - Blow Out a Candle Using Science Updated December 05, 2014. You know you can put out a candle flame by pouring water on it. In this science magic trick or demonstration, the candle will go out when you pour 'air' onto it. Candle Science Magic Trick Materials a lit candlea transparent glass (so people can see what is inside the glass)baking soda (sodium bicarbonate)vinegar (weak acetic acid) Set up the Magic Trick In the glass, mix together a little baking soda and vinegar. How to Blow Out the Candle with Chemistry Simply pour the gas from the glass onto the candle. How the Candle Trick Works When you mix baking soda and vinegar together, you produce carbon dioxide.