Emulsion, oil/ water coloring droplets

Cleaning the fryer back home is not exactly easy. Who usually does this knows that is a messy, sticky and dirty work. To minimize this greasy effect we usually fill the fryer with boiling water and add detergent on a very generous amount. In fact I usually pre wash all the dishes before putting them in the machine. Why? Because it allows the fat to dissolve in the water and not inside the machine or in my hands.

Why?
Because the detergent is an emulsifier, and as such promotes the formation of emulsions.
An emulsion is a system consisting of two immiscible liquid phases (oil and water). We may have emulsions of oil in water (O / W: external aqueous phase) and water in oil (W / O: oily external phase).
The emulsion stability is ensured with use of emulsifying agents such as detergent, surface-active substances generally.

We will need:

• 3 transparent cups, glass or plastic,
• water, enough to fill two cups,
• cooking oil,
• food coloring,
• pencils.

How to:

1. Fill one of the containers with water (2/3) and the other with the same amount of cooking oil;
2. Add 3-5 drops of food coloring to each, leave some space between the drops so that they do not touch each other;
3. What happens?
4. Fill the third container with water up to 2/3, add some oil, enough to form a layer on top of the water.
5. Add the food coloring the same way as in the previous point. Try to predict what will happen;
6. What happens?
7. With the sharp pencil touch a droplet of colorant of the third cup;

What happens?
When the food coloring is added to water, it blends completely with it. When you add the same food coloring to the oil, a small sphere is formed on oil surface.

Why?
Water molecules are polar, in other words they have a small positive charge at one end and a small negative charge at the other, for this reason they remain together, by forming hydrogen bridges. Unlike water molecules, the oil molecules are non-polar - have no charge-, for this reason, the molecules of oil also tend to stick together.

When we "force" an oil to mix with a water based solution (the food coloring) those form an emulsion.
A emulsifier it's a molecule with to different ends, one that loves water (hydrophilic) and a second that hates water (hydrophobic). Imagine a wood stick with two ends, one of them "sinks" in the oil- the hydrophobic end- the other in the water- hydrophilic end. This phenomena is responsible for the formation of small oil droplets -spheres- in the water. This is a stable structure and it's what we call emulsion, many things around us at home are emulsions like mayonnaise and face creams, for example.
If you try to mix the jar 3 emulsion you will verify that after a while the oil will came back to the top..

When you use food coloring (FC), what happens is that the FC droplets drag a small amount of oil with them as a "coat", that's why the FC stop in the oil. the oil acts as a life saver coat, preventing the droplets to drawn. When you punch the droplets with the sharp pencil, the "oil coat" is broken and the FC- a water based solution- blends, almost immediately, with the water bellow the oil. 

Go further
If you want to go further change the variables, one at time and take notes.

• Use different kitchen oil types;
• Use vinegar or any other kitchen liquid instead of FC.

Et voilá!
Now you can avoid your daily bath: "Mom I'm hydrophobic!"

Enjoy!

Growing crystals at home

What is a crystal?
Crystals are regular structures formed by a regular repeating pattern of atoms or molecules.

These structures grow by a process called nucleation. During nucleation, the atoms or molecules of what we want to transform in a crystal (solute) are dissolved in a solvent. The particles of the solute will tend to cluster together, forming subunits of atoms or molecules. These larger particles will also group with each other and eventually become large enough to "pop out" the solution (crystallize).

Other solute molecules will continue to adhere to the surface of the crystal, causing it to grow until equilibrium is achieved between the solute molecules in the crystal and the solution.

Growing crystals
Three factors that can influence the growth of "home" crystals:

• A good/poor solution saturation- The first stage of home crystal growth is a saturated solute. In a saturated solution the probability of molecules colliding with each other in order to form a core for initiating nucleation is greatly increased.

• Surface type-A rough surface tends to be more attractive for nucleation. It is more likely that a crystal is formed on a piece of rough rope than the in the smooth walls of a glass.

• The presence of deposits in the bottom-This occurs when the solution is not scrambled or means that too much solute was added to saturate the solution. The presence of these deposits create areas for optimum crystal growth however prevents crystal formation in the "target."

Lets see how to grow sugar crystals, these crystals can be sucked and eaten like a lollipop. This demonstration may take up to 3 weeks.


We will need:

• 3 cups of sugar, we have to adjust this quantity, we want to saturated at 100% but no precipitate,
• cup of water, to boil,
• food coloring,
• small jar,
• small bowl,
• wood stick, or rope,
• kitchen paper or paper filter.

How to:

1. Boil the water, careful with burns!;
2. In the bowl, mix the boiling water with the sugar;
3. Stir the water until all the sugar is dissolved;
4. If you want to give sugar some color, now it's the time, add the food coloring;
5. Place this solution in the jar, attention! wash the jar really well to avoid nucleation in it's walls;
6. Avoid any amount of sugar precipitate in the jar- any not dissolved sugar-, this sugar will be a good nucleation "start point";
7. Suspend the stick or rope in the solution, do not wash those, we want this to be a suitable "start up" spot for nucleation;
8. Chose a nice and quiet spot to place your jar for at least 3 weeks;
9. Wait until the solution cool and cover it with a paper filter. 

What happens?  
After cooling the solution will use nucleation spots to form crystals.

NOTE: You must check the jar on daily basis, if you see any nucleation in jar walls, change the jar;

Wait about 3 weeks for excellent results.

Go further:

• Follow the growing crystals with a graph;
• Use salt and compare the growing velocity with the sugar;
• Use 3 jars, in the first one use boiling water, in the second tepid water, and in the last one repeat the essay with cold water;
• Try to dissolve the sugar/salt/other while the water is boiling;
• I am sure you can remember other ways to change this demonstration into a experiment...

 Source: about.com; squidoo.com; buzzle.com
Et Voilá!
Science you can eat!  

Enjoy!

Nature finds a way- light labyrinth

It's amazing how the sentence "Nature finds a way" is incredibly correct, everyone knows at least one story about animals saving people or about animals doing thousands of  km despite the unimaginable difficulties- like monarch butterflies or salmon going up the river.

Nature follows a small set of rules that allow ecosystems to function in equilibrium theoretically "ad eternum" if they are not disturbed by the "human hand".

Today I bring you a demonstration of how nature always finds a way to overcome the difficulties.
The test is very simple allows direct observation of the struggle for life.

We will need:

• potato;
• small plastic container/pot, like a cup,
• soil,
• shoe box,
• wooden blocks, legos®, or other small obstacles.

How to:

1. Allow the potatoes a few weeks at room temperature, so they can germinate, this procedure should be done in dry conditions, with light and warm. This procedure can take up to 6 weeks; 
2. Take the potatoes and place them in the container with the "little eyes" facing upwards;
3. Cover the potatoes with moist soil;
4. In the narrow side of the box make a round hole the size of a small coin;
5. Put the pot inside the box at the opposite end to the hole that opened in the box;
6. build small walls and obstacles using the legos®;
7. Place these obstacles inside the box, make sure that there is at least one free path to the hole, don't close the hole;
8. Close and seal the box, make sure no light can get in except from the hole;
9. Place the box somewhere with direct light with the hole facing the light source;
10. Wait 3 or 4 days and observe.

What happens?
After a while the potato will grow in light direction, sprouts will naturally go around obstacles in light direction

Why?Because the plant needs light to produce food, and thus growth will always be towards the light.
 
Go further: 
Repeat this with other plants.
"Do all plants grow in the same way?" 
you can use dry beans, onion.
 
Et Voilá!
Nature finds a way!

Enjoy!

The air takes up space- ballon in a bottle

The challenge is to blow a balloon inside a plastic bottle. A big bottle works better but you can use a small bottle if you want. But is it that easy? Lets see

What we need:

• plastic bottle and stopper,
• latex balloon,
• water,
• nail,
• hammer.

How to:

1. Place the balloon inside the bottle, with the tip out;
2. Try to inflate the balloon, try again!;
3. Remove the balloon;
4. Fill the bottle with water and cap it tight;
5. With the nail punch a hole in the bottle bottom; 
6. Remove the nail and uncap the bottle, what happens?,
7. Leave only a small amount of water in the bottle;
8. Place the balloon inside the bottle again, just like in step 1;
9. Try to inflate the balloon, what happens?;
10. When the balloon is full of air, use your finger to close the nail hole;
11. Stop blow, what happens?;
12. Now remove your finger, what happens?

What happens?
In step 2, you aren't able to inflate the balloon.
When you remove the nail and uncap the bottle- step 6- the water exits the bottle through the hole.
Step 9-  you are successful.
While your finger is in the hole the balloon will remain full of air- Step 11.
If you remove the finger the balloon deflates.

Why?   
Step2- The bottle is full of air, there is no room for anymore air.
when you punch the hole in the bottle the air can escape through it and and "make some space" to the air in the balloon , while you inflate the balloon it "pushes" the air and the water inside the bottle to the outside through the hole.
Same reason explains why the balloon remains inflated in step 11 and deflates in step 12, amazing humm?



Et Voilá!
It takes space

Enjoy!

Grow Stalactites with a string

Mira d'Aire

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:

1. Fill a glass twice with water and dump it in the pot,
2. Add 1 Epsom table spoon;
3. Mix;
4. Repeat again and again until the solution is saturated;
5. Heat the heat the pot on a stove, caution!
6. Add more salt and keep stirring, hot water can  dissolve more salt, do not boil the water;
7. Split the water for the 2 glasses, try to be the more exact as you can;
8. Find the location where they will sit for the next few days...;
9. Leave a 3 or 4 inches between the glasses;
10. Cut a string big enough to cover the distance between the glasses and hang down to the bottom of both glass;
11. Tie the paper clips in both string ends;
12. Place each one on a glass;
13. Wait, observe ad take notes.

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

Et voilá!
Geology in the kitchen

Enjoy!

Floating pin

Another demonstration. So simple but so interesting

What we need:

• straight pins,
• water,
• toilet paper,
• bowl.

How to:

1. Fill the bowl with water;
2. Wait a few seconds until the water stop moving;
3. Can you place a straight pin floating in the water? Try it;
4. What happened?
5. Try a second pin.
6. Place the pin on the top of  a piece of toilet paper;
7. Place both things in the water, very carefully and gently
8. 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.

Et voilá!
It's magic! No, it's science!

Enjoy!

Electric and bouncy pepper

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:

1. Mix some pepper and salt in the plate,
2. Mix well, use the fork to help you;
3. Ask your restless to separate the salt from the pepper, humm... tricky uh?;
4. Rub the fork in the cloth for 30-60sec;
5. 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.

See the movie:

You can learn more about this here.

Et voilá!
Bouncy pepper!

Enjoy!

Jumping paper circles

This is a classic! A electric balloon full of static electricity
What we need:

• 1 balloon,
• 1 wool cloth, you can use your hair,
• 1 paper hole puncher,
• old paper, reuse some old paper.

How to:

1. Blow the balloon;
2. Punch some holes in the paper, fold the paper several times before you use the puncher, that will give you more circles;
3. Rub the balloon in your hair or in the cloth;
4. Approach the balloon and the paper circles.

What happens?
The circles "jump and glue" to the balloon walls.

Why?


Although this is a very simple and basic demonstration some of us never stop to think about what is really going on.
The paper and the balloon are made of atoms. This atoms have a positive core surrounded by negative electrons, these move around the core.
As we saw here several times everything tends towards an equilibrium and thats why almost everything that surround us is charged with a neutral charge. Is the same as saying that the sum of its charges is 0.


Repulsion and/or attraction are only possible if the charges of both materials are different in sign. That means: repulsion and/or attraction are only possible when the objects have excess or lack of electrons and because of that have a negative or positive charge.

When the balloon was rubbed it passed from a resting state to a excited state, and therefore electrically charged(in this case with excess negative charge).

Why the balloon become charged? This was possible because the cloth and the balloon have different characteristics, one can receive electrons and the other can give them, despite they are both in a rest state to begin with. This means one is electronegative (easier to receive negative charges, balloon), and the other is electro-positive (easier to donate negative charge, hair or cloth), when two such materials are rubbed, negative charges migrate from one material to another, when are removed one is positively charged and the other negatively. If you use the hair you will find that it "will glue to the balloon."

The paper was in a rest state, neutral charged. If that is true why does it jumps to the balloon wall?

Yes, the paper was not charged.

The attraction between a neutral charged material and another can be explained using the idea of electrical dipoles, a phenomenon commonly referred to as "charge separation" (in Figure). This separation happens when neutral object is subjected to the action of other electrical charges, in this case electrical charges of the balloon, thats why the paper circles "jump" to the balloon, attracted by the negative charges.

Note: This electrical phenomenon only occurs between insulating materials, conductive materials do not have the ability to retain electric charges, as they seep through the material.

A step further:

• Change the rubbing time;
• Change the friction material (cloths can try silk, cotton, wool ...);
• Change the amount of air in the balloon.
• Make a table to record your results.

ATTENTION:
Do not forget the first rule: do not change more than one variable at a time.

sources: cienciamao.usp.br; eurekahandsonmindsonscience.blogspot.com

Et Voilá!
So simple so scientific

Enjoy!

Floating lemmons, or not

Observation:
Peeled lemons sink, unpeeled lemons float.

Why is that? Maybe the lemon peel acts like a lifebuoy, keeping the lemon above the water line.  

What we need:

• water,
• small box or a glass container, transparent,
• 1 lemon,
• your lab notebook.

 How to:

1. Fill the container with water, enough to float lemon;
2. Place the lemon inside the container;
3. Observe carefully what happens and record the results in your notebook;
4. Remove the lemon from the water;
5. Peel the lemon;
6. Place it again on the water;
7. Observe carefully what happens and record the results in your notebook.

Attention: Ask an adult o handle the knife

 

What happens?
Peeled lemon sink, unpeeled lemon float.

Why?
Notice that when the lemon was unpeeled it only sunk enough to stabilize its weight. In the picture you can see 1/4 of the lemon off water.

This is due to, at least, two factors, density and porosity.

Density, density depends on lemon weight and volume. But if we peel the lemon it becomes lighter nevertheless it sinks.

Porosity, Lemon peel is extremely porous and when placed in water, the air is trapped in these pores and can not escape, this makes the lemon float. Just enough to compensate its weight.

By simple observation we can see that the peel is made off two areas, a white and spongy one and a yellow and porous one. What if we separate this yellow and white areas?

1. Place the lemon peel in the water. Does it float?
2. Observe carefully what happens and record the results in your notebook;
3. With a knife separate the yellow section from the white section;
4. Try to place the white section in the container. Does it float?;
5. Observe carefully what happens and record the results in your notebook;
6. Now try with the yellow exterior section;
7. Observe carefully what happens and record the results in your notebook.

"The peel white section" floats! The yellow one sinks!
If you look closer you can see that the white section is very spongy, and therefore very light, ie works as a buoy.

In terms of evolution, in which only the fittest survive, we see this floating lemon as a competitive advantage, the fruits may fall from the tree, float in a water course and travel to other destinations and lands where their seeds can proliferate at will.


A step further:

• Use different citrus, like lime or orange.
• Use different fruits like  apples or bananas.
• In nature we can find different thicknesses of peels in lemons. Do the peel thickness affect the outcome?

Et voilá!
Archimedes in action.

Enjoy!

Food coloring chromatography

QUESTION: Is it possible to separate the colors of a mixture of food colorings after they have been mixed?

What we need:

• coffee filters,
• wooden skewer,
• food coloring, yellow, green and blue,
• 4 glass containers,
• markers
• 4 paper clips,water.

How to:

• Prepare the work area, chose a easy to clean zone in outside or in the kitchen, food coloring usually leave messy stains;
• Identify the bottles, assign one or two letters each color, e.g. bottle Ye (yellow) Bl (blue) Gl (green) and Mix (mixed colors), or simply ABCD, write down in your notebook which is which.
• Place 6 drops of yellow dye in the bottle Ye;
• Dilute the food coloring with 30ml water;
• Repeat this procedure for both blue and green dye;
• In the last bottle (Mix) place 2 drops of each dye and diluted as usual;
• Prepare the coffee filter, cut it in 4 identical strips;
• Put a strip of paper in each bottle, as pictured;
• Use the paper clips to keep the paper in place;
• Wait until the dye reach the top of the paper, we wait 15min, may be more or less depends on the brand of the dyes.
• After the dye reach the top of the paper remove it from the cup and put it on a horizontal surface;
• Wait until it dries;
• Observe the color patterns.

What happens?
The water climbed the paper and the food coloring dissolved on it formed patterns in the paper.
In pictures you can see we used circle and strip paper, the results were exactly the same for the used colors.

Why?
Chromatography is, as its name indicates, writing (spelling) colors (chrome) and is one of the main techniques that biochemists use to separate mixtures.

First, before attempting to answer our question, it would be necessary to state three things:

• The first is that we must have a control, in this experiment a bottle with solvent without the dye, to exclude any possible interference of anything, We have done it, but does not appear in pictures. We did not observe any color band in this “blank”.
• The second is that the solutions were made with 6 drops of dye to 30 ml water, it’s possible you might get different results when using different trademarks and/or dilutions, so in science it is very important to control everything, even the brand of reagents.
• And thirdly, we have to study the individually solution behavior so we can interpret the Mix results.

Control: No bands or spots of any color.

Green dye: Shows three colors, blue on top of the paper, a broadband green and a darker line on the base. We could observe a yellow band between the larger green band and the darker line at the base.
In the label on the bottle we can read: ”Contains yellow dye and green dye“ that way is normal o have a green and a yellow band in the paper, but where did the dark line came from? A closer look give us the answer: the darker line is a dark blue zone. Blue? Yes blue. That’s because green is the mix of the blue and yellow color. 

Yellow dye: the coffee filter paper was completely yellow. With a yellow zone more pronounced in paper, yellow is a primary color, and in the label doesn’t say anything about any addition of another type of dye.

Blue dye: We can see that the filter has three distinct zones (note the small strip in the photo), back lit we see one of the area's violet (on the color wheel this is the result of mixing blue and magenta) the second zone is blue, and the third band is a second kind of  blue, lighter and more prevalent, one is cyan, and the other is an unknown color we would probably only find out for sure using more advanced analysis techniques.

On the blue label we can read: “contains blue dye and E122”. What is this E122? The website ukfoodguide.net describe it as a carmine food coloring, the presence of this E122 may explain the violet band observed at the base of the paper.




After observing and interpreting individual results we will then look to the mix filter:

One large blue zone followed by a green one. Between them we can see a faint yellow band, in the base we can’t see the violet line or brown stain which would be expected by the presence of green dye, instead we can observe a dark indistinguishable line. Back lit we can see some violet color, but nothing conclusive. Probably this phenomenon is due to the fact that the carmine E122 and the brown present at the bottom of the paper requires more time and /or longer/ different kind of  paper to separate and become visible.

The answer to the above question is “Yes it is”. However it is necessary to improve the used technique.

A step further:

• Improve the separation method:
• Using different dilutions;
• Different filter papers;
• Bigger filter papers;
• See if you can see these bands, eventually even be surprised by other bands that become visible.

Et voilá!
A true experience!

Enjoy!

Dancing raisins in soda

QUESTION:
Will the CO2 released from a water with gas bottle be strong enough to take to the surface 6 raisins?

What we need:

• transparent glass,
• water with gas, the strongest work best,
• 6 raisins

How to:

1. Chose a easy to clean zone near the sink;
2. Fill the glass with the carbonated water, use a medium glass, if its too large the gas will escape to fast;
3. Drop the raisins in the water;
4. Observe.

What happens?
The raisins will go up and down in the water for a while.
Why?
The CO2 gas in water begins to free itself when we first open the bottle. This CO2 travels vertically through the glass until it comes into contact with the air, at this poit the gas is released into the atmosphere.

When the bubbles of carbon dioxide meet the raisins those are immediately trapped in the grape rough skin imperfections, which will do the raisin “move up” to the top. When they arrive at the top CO2 bubbles are released in the air and the raisin falls down o meet another set of CO2 bubbles and go up again, and the cycle repeats itself. This will happen until there is not enough CO2 in the water to elevate the raisins.

Make this demonstration a true experiment:

• Use vinegar and baking soda. This mix will produce CO2. Do the raisins dance? Use plain vinegar with no additives
• Use other carbonated beverages.
• What drink is most effective?
• Try to use drinks with sugar and with no sugar. Do you notice any difference in the dance?
• Repeat the experiment using plain water and effervescent Alka-Seltzer® tablets.

Remember, record all your observations so you can quickly draw conclusions. Use a timer to tell time.

Et voilá!
Raisins dancing!

Enjoy! 

It's magic? No it's Science

With water, and a cardboard you can do a little magic with your restless.
This water is defying gravity.
Thats because the air in it can't escape to let in new air.

Et voilá!

It looks like magic, it sounds like magic, it tastes like magic, but it's science!

Enjoy!

Measuring time with a candle

Clock: Any instrument for measuring time intervals.
Dicionários Porto Editora

The clock is one of the earliest inventions of mankind. The first instruments used to measure time were based on solar motion and daylight. These mechanisms had a huge problem; in order to work the sun has to be visible.

Because of this fact it soon becomes obvious that it was necessary to find other methods "to read" the time, methods that were not dependent on weather conditions. Soon people find other mechanisms to track the time such as the hourglass, in which a small amount of sand is placed in a container which has a small hole in the base witch allows the sand to a second container, by changing the amount of sand and / or the hole size is possible to change the velocity of the sand, this mechanism is still used in some community games, it is effective and visually pleasing.

Water clock

Another mechanism is the water clock. This clock like an hourglass consists of two containers, initially empty, the containers and placed one above the other. The top container has a hole in the base; the other one has a scale. We fill up the top container that will "pouring water" to the second container.

Today we use clocks with milimetric precision, and we have atomic clocks that set universal time. The website zenite.nu, states that until 1986 the Greenwich Mean Time or GMT was used as the world standard but was replaced by the Coordinated Universal Time ou UTC, which is based on atomic standards

Sun clock- Lisbon Cathedral walls

UTC is the world standard accepted by "International Bureau of Weights and Measures".
0.00 UTC still means 0.00 in the GMT standard.

Today we are going to build a candle clock.
It's simple to understand and easy to work with.

What we need: 

• 2 candles, similar,
• string,
• black marker,
• 2 candle holders,
• 1 dish,
• a few bolts,



Hourglass

• clock.

How to:

1. Make sure the candles are similar, size and thickness;
2. Place both the candles on the candle holders;
3. Light the first candle;
4. Count 10 min, you can set an alarm;
5. When the alarm goes off make a mark with the pen in the second candle, marking the high of the first candle after 10 min;
6. Repeat the step 4 and until the first candle runs out.
7. At the end you should have a candle like the one in the picture;
8. Tie the bolts to the candle, one in each pen mark;
9. Place the candle+ candle holder in the dish;
10. Light the candle.

Marked Candle

What happened?
Every10 minutes a bolt will fall in the dish, working as an alarm.

Why?
The first candle works like a standard, we used it to know the rate of burning of the second candle, that’s why it's important both candles are similar.
Of course this clock is completely inaccurate, but it’s a good start. We can read in many candle tags its estimated life time, this is always only a reference, in fact a candle duration is related with many factors.
Another thing we must have in mind is that the "marks" on the second candle were made without using a measuring instrument.

If you want to go further:

Industrially marked candle

• Use the ruler to mark 1/2 inch segments on the candle, light it and measure the time it takes to get there. Answer the question: All segments take the same time to burn? Why?
• Get similar candles in different colors. Do they all burn at same rate?
• Get similar candles, all at same color but with different brands. Do they all burn at the same rate?
• Get similar candles, all at same color and brand but with different wax. Do they all burn at the same rate?

Important:

• Use at least 3 candles of each to get more accurate results. You will take the average at the end;
• Change one, and only one variable at time, otherwise you will not be able to get a real cause/effect;
• Take note of all results and observations in your notebook

Warning: The candle is hot, caution! Do not move the candles while the experiment is going. 

References:
http://www.sobre.com.pt; http://www.infopedia.pt; http://www.zenite.nu; Mandell, Muriel, 1998, "Experiências Simples sobre o tempo com materiais Disponíveis" Bertrand Editora

Et voilá!
You will never let the time fly again.

Enjoy!

Overcome the force of gravity

When we add salt to water we increase its density, which will allow some objects to float.

What we need:

• 6 glass jars,
• different objects, like beans, grains, paper clips, eggs, etc.. we used dry beans, dry grain and an olive;
• salt,
• dessert spoon,
• water,
• pen,
• labels,
• your notepad.

How to:

1. Clean the jars;
2. Label them with letters or numbers;
3. Select the objects you want o test,
4. Write on your notepad which letter goes with each object, one of the jars will be the control, for example A- control; B- olive; C- bean....;
5. Fill the jars with the same quantity of water, we used 250ml;
6. Verify if any of your objects floats;
7. Write down your results;
8. Take the objects from the jar;
9. Add 1 dessert spoon of salt to the B jar, 2 to the C, 3 to the D... don't add any salt to the first jar (control);
10. Mix it well until the salt is all diluted, if you are using jars with lid is easier to close the jar and shake;
11. Test all the objects, one by one, jar by jar;
12. Write down your results.

At the end you will have precise notes about the number of spoons you need to add to water in order to float  a certain object.

These were our results:

A- 0 salt
B- 1 salt
C- 2 salt
D- 3 salt- floats: grain
E- 4 salt- floats: red bean; black bean
F- 5 salt- floats: white bean; olive

Attention: you may get different results; those depend on the beans/grain/olive trademark, size and water content.

It's possible to find on internet and some books some references to some restless minds that made heavier objects to float, like marbles, or stones, using larger amounts of salt. We didn't test those objects, in theory, yes it's possible to make it happen, but the amount of salt in the water will be hugely high.
Accept this challenge and try to float denser objects.

What happens?
As you salt the water, this will become denser, in other words, heavier. This density is closely linked to the force that water exerts on the items, if this force is higher then the force that pushes objects down (gravity) the objects are boost up and float.
With this experiment you can also observe water saturation, write down the number of salt spoons you need to saturate the water.

It is possible to do some variations to this essay:

• Use only one kind of bean but with different water levels (1 dry, hydrated but raw and 1 cooked);
• Use only one kind of bean with different water levels, from 3 different trademarks (dry, hydrated, cooked from trademark A, dry, hydrated, cooked from trademark B; dry, hydrated, cooked from trademark C);
• Use green olives or black, with pit, without pit...

Write down your results.

Et voilá!
Can you make it work with the marble?

Enjoy!