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Science progress affects our daily life and "to know" means you are going to chose right, because it allows you to form your own opinion on scientific everyday issues. On the other hand, having an elegant and harmonious vision of the world where we live in leads to a feeling of intellectual satisfaction.
We believe this kind of scientific day to day knowledge should be encouraged from an early age, and that's why this project was born: science, culture, knowledge, crafts for your restless mind.
Stalactite:
a cylindrical mass of calcium carbonate hanging from the roof of a limestone cave: formed by precipitation from continually dripping water
Alvado
Stalagmite
a cylindrical mass of calcium carbonate projecting upwards from the floor of a limestone cave: formed by precipitation from continually dripping water
in http://www.thefreedictionary.com
Let´s try to do our own stalactites and stalagmites, with water and salt.
At first sight may look simple and easy, but in fact is a lot difficult because it will depend on a lot of variables.
What we need:
Epsom salts,
water,
2 identical glasses,
string or paper towel,
2 paper-clips or weights,
spoon,
bowl or pot,
a good place to leave the glasses siting for a few days
How to:
Fill a glass twice with water and dump it in the pot,
Add 1 Epsom table spoon;
Mix;
Repeat again and again until the solution is saturated;
Heat the heat the pot on a stove, caution!
Add more salt and keep stirring, hot water can dissolve more salt, do not boil the water;
Split the water for the 2 glasses, try to be the more exact as you can;
Find the location where they will sit for the next few days...;
Leave a 3 or 4 inches between the glasses;
Cut a string big enough to cover the distance between the glasses and hang down to the bottom of both glass;
What happens?
After a few days we will notice a little stalactite on the string.
With a bit of luck you will be able to see a stalagmite too.
Why?
The water travels through the string and the salt goes with it. While the path is vertical the salt "plays along" with water, but when the path becomes vertical, the gravity wins and the saltwater is pulled down. The water trickle and leaves the salt behind on the string. With time the salt will form a stalactite. If you are lucky and wait enough time you will be able to see the stalagmite formation, under the stalactite.
NOTE THIS:
This demonstration is not so easy as it seams.
You need a strong and concentrate solution of salt;
For better results immerse the string in the solution, before you place it between the glasses.
If the water is dripping very fast increase the distance between the cups, that will reduce the inclination angle.
Do not use a wood surface, it may damage the wood.
A step further:
Use different strings;
Use other salts;
Use different concentration solutions;
Important:
Change one thing at time;
Register everything
Sources:http://www.sciencekidsathome.com, Dicionário de Mineralogia e geologia ilustrado
A terrarium is a completely self-sustaining ecosystem in a container that is designed to house small animals and plants under controlled conditions.
The closed nature of a terrarium creates an environment easy to control, allowing the simulation of environments from desert to rain forest.
In general it is made in a clear naked container, but can also be constructed in wood, for example.
The top can be open or closed depending on the environment we want o recreate. When open it's protected with a net to prevent the "escape" and the entrance of living beings.
How does it works?
The plant resets the oxygen, the light is a source of energy, the water comes from moisture in the soil. As the dead leaves fall and decompose providing food for the soil.
We can build a Terrarium, that's today proposal.
What we need:
transparent glass container, with a wide opening,
small stones,
activated charcoal, you can buy it in a pet shop,
potting soil,
small sponge,
a net with a fine mesh
canvas
moss and/or plants.
How to:
Chose what plant you want to use, they must be small and slow growth;
Place the small stones in the container -terrarium;
Spread a small amount of activated charcoal on the top of stones;
Take a piece of canvas and make a small cut in the middle
Cover the charcoal with the canvas;
Place a sponge (with 3cm wide) in the canvas cut, this will take the moisture to the plants;
Cover the all hing with soil;
Place the plants. Just like you will do it in the garden;
Spray your plants with water;
You can add o your garden some action figures;
Close the Terrarium with the net;
Wait to see if it works.
At first the Terrarium will look fragile, but after a few days the ecosystem will start operating normally. It's normal if the first try fail, but don't give up, use different plants and different soil and try again.
Another demonstration. So simple but so interesting
What we need:
straight pins,
water,
toilet paper,
bowl.
How to:
Fill the bowl with water;
Wait a few seconds until the water stop moving;
Can you place a straight pin floating in the water? Try it;
What happened?
Try a second pin.
Place the pin on the top of a piece of toilet paper;
Place both things in the water, very carefully and gently
Wait a few seconds.
What happens?
The paper sinks, the straight pint floats.
Why?
Surface tension, that's the answer.
When we place the pin in the water, without using the paper, it immediately sinks, its weight is too high for the area it occupies, ie is very dense.
The paper, by contrast have much area for the weight, in fact it doesn't sink, actually it soaks, in other words water molecules fill the paper pores in it's porous structure and fill the voids in the web cellulose paper. this way the paper becomes heavier and sinks.
Surface tension is responsible for what one might call "skin."
The water surface is formed by a barrier of water molecules. This barrier is what allows insects to land on water, the soap bubbles to exist, and the pin does not sink.
The first pin sinks because it doesn't start from a position of equilibrium and rest, unlike the second which is resting on the paper. The paper when sinks exerts sufficient force on the skin of the water to bend it but not to break it, and the pin floats.
This is another version of the Jumping paper circles demonstration.
Today we will use black pepper powder. What we need:
black pepper powder,
salt,
wool cloth,
plastic fork or spoon,
plate.
How to:
Mix some pepper and salt in the plate,
Mix well, use the fork to help you;
Ask your restless to separate the salt from the pepper,humm... tricky uh?;
Rub the fork in the cloth for 30-60sec;
Approach the fork and the plate, keep the fork 2,5cm away from the plate.
What happens?
The pepper jumps to the fork, leaving salt behind
Why?
When you rub the fork with the cloth it becomes negatively charged, pepper is positively charged. That means, when you approach the fork the pepper is attracted to it, and "jumps".
The salt is also negatively charged but is slightly heavier and it doesn't jump so easily. However, if you don't keep fork distance the salt will eventually jumps, thats because the electrical attraction overcomes the weight.