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Discussion in 'Jukwaa la Elimu (Education Forum)' started by SMU, Jan 10, 2009.

  1. SMU

    SMU JF-Expert Member

    Jan 10, 2009
    Joined: Feb 14, 2008
    Messages: 6,895
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    Why does wet fabric appear darker?
    When fabric gets wet, light coming towards it refracts within the water, dispersing the light. In addition, the surface of the water causes incoherent light scattering. The combination of these two effects causes less light to reflect to your eyes and makes the wet fabric appear darker.

    Why does water not calm the tongue after eating hot spicy food?
    The spices in most of the hot foods that we eat are oily, and, like your elementary school science teacher taught you, oil and water don't mix. In this case, the water just rolls over the oily spices.

    What can you do to calm your aching tongue? Eat bread. The bread will absorb the oily spices. A second solution is to drink milk. Milk contains a substance called "casein" which will bind to the spices and carry them away. Alcohol also dissolves oily spices.

    Why is blue for boys and pink for girls?
    In ancient times, it was believed that certain colours could combat the evil spirits that lingered over nurseries. Because blue was associated with the heavenly spirits, boys were clothed in that colour, boys then being considered the most valuable resource to parents. Although baby girls did not have a colour associated with them, they were mostly clothed in black. It was only in the Middle Ages when pink became associated with baby girls.

    Why is it called a "loo?"
    The British word for toilet, "loo", derives from the French "garde a l'eau!" In medieval Europe people had little conception of hygiene and threw the contents of their chamber pots out the window into the street below. In France the practice was preceded by "garde a l'eau!" ("watch out for the water!"). In England, this phrase was Anglicised, first to "gardy-loo!", then just "loo", and eventually came to mean the toilet/lavatory itself. The American word for toilet, "john", is called after the John Harington who in 1596 invented an indoor water closet for Queen Elizabeth I.

    Why is the sky blue?
    When sunlight travels through the atmosphere, it collides with gas molecules. These molecules scatter the light. The shorter the wavelength of light, the more it is scattered by the atmosphere. Because it has a shorter wavelength than the other colours, blue light is scattered more, ten times more than red light, for instance. That is why the sky is blue.

    Why does the setting sun look reddish orange? When the sun is on the horizon, its light takes a longer path through the atmosphere to reach your eyes than when the sun is directly overhead. By the time the light of the setting sun reaches your eyes, most of the blue light has been scattered out. The light you finally see is reddish orange, the colour of white light minus blue.

    Why do onions make you cry?
    Onions, like other plants, are made of cells. The cells are divided into two sections separated by a membrane. One side of the membrane contains an enzyme which helps chemical processes occur in your body. The other side of the membrane contains molecules that contain sulfur. When you cut an onion, the contents on each side of the membrane mix and cause a chemical reaction. This reaction produces molecules such as ethylsufine which make your eyes water.

    To prevent crying when you cut an onion, cut it under a running tap of cold water. The sulfur compounds dissolve in water and are rinsed down the sink before they reach your eyes. You can also put the onion in the freezer for ten minutes before you cut it. Cold temperatures slow down the reaction between the enzyme and the sulfur compounds so fewer of the burning molecules will reach your eyes.
    Last edited: Jan 10, 2009
  2. SMU

    SMU JF-Expert Member

    Jan 14, 2009
    Joined: Feb 14, 2008
    Messages: 6,895
    Likes Received: 716
    Trophy Points: 280
    Why you shouldn't smoke

    Tobacco is a $200 billion industry, producing six trillion cigarettes a year - about 1,000 cigarettes for each person on earth. And this is what you'll find in cigarettes:

    ~ Formaldehyde, which embalmer use to preserve dead bodies;
    ~ Toluene, which is commonly used as an ingredient in paint thinner;
    ~ Acetone, an active ingredient in nail polish remover;
    ~ Ammonia, which scientists have discovered lets you absorb more nicotine, keeping you hooked on smoking.

    If you smoke, you're also inhaling arsenic, benzene, cadmium, hydrogen cyanide, lead, mercury and phonol. In all, 4 000 harmful chemicals, including 44 types of poison, of which 43 are proven cancer-causing substances.

    Bad business
    Life insurance companies charge smokers nearly double the amount they charge non-smokers for term assurance. Some tobacco companies also own shares in life assurance companies. What appears to be a good deal for tobacco companies is a bad deal for taxpayers: the health care costs caused directly by smoking, and the lost economic productivity, cost governments up to three times as much as the total earnings of the tobacco industry.

    Smokers are ten times more likely to suffer from lung cancer than non-smokers, three times more likely to have a stroke, and twice more likely to suffer a heart attack. Carbon monoxide in cigarettes deprives the heart of oxygen. Smoking can cause headaches, infertility, blood vessel disease, digestive problems, mouth and throat cancer, and blindness.

    Tobacco causes more deaths than those caused by all the wars of the past 100 years, including World Wars One and Two. More than three million people die each year as a result of smoking.

    Nictonine is a drug. It is more addictive than cocaine, heroine or mandrax. Nicotine is a natural insecticide. Plants such as tomatoes produce it in their leaves to discourage bugs from eating them.

    Stop smoking
    - After 8 hours, the carbon monoxide in your blood drops to normal.
    - After 48 hours, nerve endings start regrowing and the ability to smell and taste is enhanced.
    - After a year, the risk of heart disease drops halfway back to that of a non-smoker.
    - After 15 years, the risk of coronary heart disease is that of a non-smoker.