Good bye friends

Une monnaie capricieuse

Le matérial dont nous avons besoin pour réaliser l'expérience est:

Un verre
Une monnaie
Une carte d'un jeu de cartes

Préparation

Mets la carte sur le verre et la monnaie au centre de la carte.
Fixe le verre avec une main et tire la carte avec l'autre main avec énergie.
Le monnaie tombe dans le verre.

Qu'est-ce qui s´est passé?

La résistance d´un corps à changer son état de repos ou de mouvement s´appelle inertie.
Après avoir tiré la carte, la force de frottement entre la carte et la monnaie tend à deplacer la monnaie sur la carte. Si nous le faisons avec énergie, la force de frottement ne réussit pas à surpasser l´inertie de la monnaie qui tombe dans le verre. Mais si nous tirons lentement de la carte, la monnaie se déplace sur la carte.

Vous avez compris?

Begoña et Julia

La chaleur de nos mains

Le matériel dont nous avons besoin c´est:

Un pot de verre avec un couvercle
Une paille de rafraîchissement
Colle
Alcool

Nous pouvous faire un trou sur le couvercle avec un marteau et un clou.

Nous mettons la paille dans le trou et nous remplissons d´alcool le pot (plus ou moins deux centimètres). Et nous plaçons le couvercle.

Nous couvrons le pot avec nos mains et nous voyons que l´alcool monte par la paille.

Explication

La température de notre corps est supérieure à la température de l´air dans le pot
Pour entourer le pot avec nos mains fournissons de l´énergie au pot et comme ça augmente la température de l´air dans le pot. Cela produit l´augmentation de la pression aussi qui pousse le liquide que monte par la paille.

Si nous levons le convercle du pot, la pression dans l´interieur récupére sa valeur originale et le liquide qui monte par la paille tombe dans le pot.

Alicia, Marta et Jiamei

Rainbow Milk

Group 5 - Elena B, Cynthia C, Karina L, Laura P - Colegiul Naţional "Mihai Eminescu" Satu Mare, România

Red, blue and yellow are called the primary colors. Just by mixing these colors, you can get all the colors of the rainbow:
RED + YELLOW = ORANGE; RED + BLUE = PURPLE; BLUE + YELLOW = GREEN

What you need: red, blue and yellow food color; 1 cup milk; dish soap; shallow bowl

Directions:

• Pour 1 cup of milk into the bowl

• Add 3 drops of red food color to one edge of the bowl

- 1/3 of the way away, add 3 drops of blue food color
- 1/3 of the way away add 3 drops of yellow
- don't mix or jiggle the bowl

• Squeeze a drop of dish soap in the center of the bowl

• Record what you see.

• What do you think happened?

Does smoke rise or goes down?

To make our experiment we need a bottle of plastic of 1´5 litres, a sheet of paper and a few matches.

First we make a couple of holes in the bottle of plastic, one in the top part and another one near the base of the bottle.

Them we take the sheet paper and cut away a rectangle of 10x15 cm (10 times fifteen). We coil the paper to obtain a small cylinder of approximately 15 cm of length. Finally the small tube of paper interferes for the top hole of the bottle.

On having ignited the small tube of paper with a match a small flame is formed and is observed that for another end of the bead goes out a column of very dense smoke that falls down inside the bottle. In the exterior scarcely there is smoke.

If we cover the low hole with a finger, the small tube of paper goes out and smoke doesn’t go out.

Explanation:

On having burned the small tube it departs from the paper it is clear in the shape of particles that, together with the gases that formed in the combustion and the air they form the smoke.

In normal circumstances, the smoke ascends dragged by the warm air of the combustion.

In our experiment, the smoke that takes place is produced in the interior part of the small tube travels along it. Inside the bottle, there is no warm air, so that, when the smoke goes out for the low end of the small tube there aren’t produced rising currents of convection and the smoke, denser that the air, it rushes to the bottom of the bottle.

by Clara, Beatriz and Inés

Spaghetti tightrope walker

Material: one spaghetti


1 Stand the spaghetti placed about your two hands.
2 It moves slowly one of the hands towards the other one without inclining the spaghetti.
3 Regardless of the hand that moves the two end up together in the center of the spaghetti that will remain in balance without falling.

Explanation:

By moving the hands, spaghetti slides without falling, keeping the gravity center between the fingers.

by Antonio and Antonio

A bottle with a hole

In order to make our experiment, we only need a bottle of water with it’s cap.

We make a small hole in a plastic bottle, about a half of its height, and we fill it full of water, while we are covering the hole.

If we remove our finger from the hole, no water comes out, but if we remove the cap of the bottle, the water starts to come out. But why?

If the cap is put, the internal pressure on the hole is equal to the external pressure and that’s why the water doesn’t come out of the hole.

But, if we remove the cap, we allow that the air comes into the top of the bottles, breaking the previous balance. The internal pressure on the hole is greater than the external pressure, so the water comes out of the bottle.

by Irene and Rafael

Cartesian Diver

Ball in the air

The air stream doesn't allow the ping-pong ball to fall.


http://www.youtube.com/watch?v=mExwPCvNRJ0

Explosion in the box

We prepared:

• a stand
• 2 empty plastic boxes; smaller and bigger so that one could be a kind of lid to the other
• a small piece ( ball) of calcium carbid ( not wet or old)
• water in the wash bottle
• matches

We made a little hole in the bottom of the bigger box. Then a piece of carbide was put in the box in such way so that the hole was higher ang water could be added on the carbide ball.
Carbide reacts with water and in the reaction we obtain a gas - acetylene C2H2:

CaC2 + 2 H2O = C2H2 + Ca(OH)2

Acetylene is flammable and it burns silently if it's pure. When it is mixed with air , explodes and throws away the upper box.



http://www.youtube.com/watch?v=A9QvpGiNgQw

Fire without matches

We carried out the experiment wich shows how to make a fire without matches.

We used potassium permanganate KMnO4 and glycerine C3H5(OH)3.

Be careful and wait while doing it, fire appears after several seconds.

http://www.youtube.com/watch?v=kpae8Xh90mI

Another balance with two forks a toothpick and fire

To make our experiment we need a pair of forks, a toothpick, a glass and a match.

First, we have to intertwine the forks with the toothpick and leave them in balance at the edge of the glass. The balance is obtained because the centre of the gravity is under the support point.

What would happen if we burnt the edge of the toothpick that is inside the glass?

A part of the toothpick is burnt, but the flame is put out when it’s at the edge of the glass and the balance of the forks is kept.

The loss of volume of the toothpick that is burnt, doesn’t affect to the centre of the gravity

by Teresa and Ángela

An eddy in a bottle

To make our experiment we need two plastic bottles of one and a half litres.

First, drill a hole in the two bottles corks.
Then, fill one of the bottles with water to about three quarters and join the two plugs per cylinder.
To unite the two bottles it can be used a tape.

It is very important the union between the bottles.

When the water on the bottles is empty is upper, it seems that the water does not fall easily to the bottle bottom, but if we give a circular motion to the bottle top and creates a swirling, water falls easily.

By placing the bottles on top, water doesn’t fall to the bottom because of the compressed air trapped in the bottle which is down. It can pass through it, as there is no room for it.

When the eddy is generated by moving the top bottle, it is communicated the air in both bottles and the water in the top bottle falls easily into the bottom bottle.

by Yulia

Drawing with sand

To make our experiment we needs a plastic bottle, sand beach and a rope.

First we have to construct a pendulum with the bottle.
Them we cut the base and make a couple of holes in one of the sides in order to pass the rope and another hole in the stopper to exit the sand filled.

If the bottle is away from the position of equilibrium it begins to oscillate, describing a trajectory that will be recorded in the soil by the stroke that left the sand that falls from the bottle.

Depending of the length of the rope and on the relationship between distances, we can get different figures.

The figures obtained are known as Lissajous figures, names after French scientist Jules Antoine Lissajous, who first observed this in 1857.

by Anabel and Teresa

The underwater drop

Materials:

1. A small container and a big glass.
2. Oil
3. Water
4. Alcohol
5. Glue and coin.
6. A spoon.

If the container is made of plastic, we stick a coin at its base in order to get more stability and avoid floating.

We fill the half a container with oil.
We put it at the bottom of the glass.
We pour the alcohol necessary to cover the container very carefully.

Then, we add water little by little with a spoon (it must slip from the wall of the glass).
Small container's surface filled with oil will adopt a convex shape until the water you add is enough. Then, the oil will separate from this container and it will have a spherical form that will remain just in the middle inside the oil and water mixture.

EXPLANATION:
First, we must know the densities of the liquids we use in the experiment.
- water (1g/ml)
- oil (0'92 g/ml)
- Alcohol (0'75 g/ml)

The oil floats in the water because it's less dense than water, but it sinks into alcohol because it's denser than it. In conclusion, you can prepare a mixture with alcohol and water because inside it, oil won’t float or sink.

by Ana, Marta and Belén

Union doesn’t make strength

The materials we need to do the experiments are a balloon and drawing pins.

First you have to push the balloon against twenty drawing pins and make sure they don't explode. The strength exerted has distributed on all the drawing pins so there isn’t sufficient pressure to explode the balloon.

The effect of strength doesn't depend only on its intensity, but also on the surface on which exerts. If the surface is very large, the effect of the strength will be spread over it all.

Next, push the balloon against one drawing pin and notice if it explodes. In this case, all the strength mass and pressure at a very specific point makes the drawing pins go through the balloon and explode.If on the contrary, the surface is small, the intensity of the strength mass over it is stronger and its distorted effect increases.

by Lourdes and Blanca

Does smoke rise or goes down?

To realize our experiment we need a bottle of plastic, a sheet of paper and a few matches.

First we do a couple of holes in the bottle of plastic, one in the top part and another one near the base of the bottle.
Then we take the sheet paper and cut away a rectangle of 10x15 cm.
We coil the paper to obtain a small cylinder of approximately 15 cm of length.
Finally the small tube of paper interferes for the top hole of the bottle.

On having ignited the small tube of paper with a match a small flame is formed and is observed that for another end of the bead there goes out a column of very dense smoke that falls down inside the bottle. In the exterior scarcely there is smoke.

If we cover the low hole with a finger the small tube of paper goes out and smoke does not go out.

Explanation:

On having burned the small tube it departs from the paper it is clear in the shape of particles that, together with the gases that are formed in the combustion and the air they form the smoke.
In normal circumstances, the smoke ascends dragged by the warm air of the combustion (currents of convection).

In our experiment, the smoke that takes place is produced in the interior part of the small tube travels along it.
Inside the bottle there is no warm air, so that when the smoke goes out for the low end of the small tube there do not take place (there are not produced rising currents of convection) and the smoke (denser than the air) it rushes to the bottom of the bottle.

by Francisco and Fernando

OIL POMP

Materials:
1 One small container and one larger glass
2 Oil
3 Water
4 Glue and one coin
5 Spoon
6 Alcohol

Assembly:
1. If the container is of plastic we put on the base one coin to give it stability and to avoid that it floats.
2. You take the small container, and you fill the container until the middle with oil and you see that the oil sets on the bottom of the glass.
3 Inside the glass you fill with precaution, the amount of alcohol that you need to cover the small container. Then with a spoon, you add, little by little, water.The surface of the oil from the small container will be more and more convex, when the water that you have added is the necessary, the oil will give off the container and will forma sphere that will be floating inside the mixture of water and alcohol.

Explanation:
The densities of the three liquids : water (1g/ml), oil (0,92g/ml) and alcohol (0,79g/ml).
The oil floats on the water because it is less dense than the water, but the oil doesn’t float on the alcohol because it is denser. So you can prepare one mixture of water an alcohol, where this oil won’t float and won’t sink until the bottom.

by Macarena, Irene and Sofía

A whirlpool in a bottle

Materials:


Two bottles made of plastic 1,5 l.
Insulating tape

Execution:

First, we make a 1 cm hole at the tops of the bottles. Then, we fill one of the bottles with 75% of water and join the bottles by means of the tops. To join the two bottles we use the insulating tape. This joint is very important, so do not be stingy with the insulating tape.


When the bottles with water is on top of the other, the water does not fall easily to the empty bottle, but if we make a circular movement with the upper bottles, it generates a whirlpool, and the water falls easily.

Explanation:

When we place the bottles full of water on the top, the water does not fall because of the low compressibility of the air, which takes up the lower bottle and does not let any space for the water to fall.
By the time, the whirlpool is generated by the air of the two bottles that passes from one to the other and the water of the upper bottle falls easily.

By Mercedes and Fátima

The extintor

Material:

- Sodium bicarbonate.

- Vinegar.

- A glass.

-Matches

- A candle

Frame up:

Put inside a glass a little of vinegar ( three or four centimetres)
Add a little sodium bicarbonate. Then many bubbles appear.
Light a candle with a match. If you tilt the glass without spilling vinegar, we see that the candle puts out.


Explanation:

The chemical reaction between sodium bicarbonate and acid vinegar producers a gas called Carbon Dioxide. This gas is heavier than the air and it stays in the glass by moving the air in the glass.
When you put the candle next to glass it´s turned off by the lack of oxygen. When you tilt the glass, it´s put out because the carbon dioxide, displace the oxygen that retain the combustion.

by José Ángel and Miguel