Water

                              WATER                                     

1. All living things are made up largely of water. Water makes up about 70% to 90% of the different kinds of bodies.

2. Without water there will be no life. Water is essential (needed) to lilfe. All forms of life, plants, animals and microorganisms depend on water for their survival.

3. Water covers more than two-thirds of the Earth’s surface. Most of the Earth’s water is found in oceans and very little water is present as fresh water in rivers and lakes.

4. Pure water is colourless, odourless and tasteless.

The changing states of water

1. Water exists on earth in three states depending on the temperature of its surrounding, depending on how hot or cold it is:

1. Solid

    Ice (when water freezes, ice is formed)

    Snow

    Icebergs (large mass of ice broken of from a glacier and floating in the sea)

    Hail

    Frost

2. Liquid

    As drinking water

    Water in ponds, river

    Rain

3. Gas

    Steam (when water boils, steam is produced)

    Water vapour

2. Temperature is a measure of the degree of hotness or coldness of an object. It is measured in degree Celsius.

3. Water reaches its maximum density at 4^oC; ie the same mass of water will have the smaller volume at this temperature. This is known as water anomaly.

4. What is density?

   Mass

Density = ----------   (Mass divided by volume)

                                      Volume

THE PROCESSES OF WATER

1. When water gain or loses heat (temperature changes), it changes its state.

2. There are five processes of water:
• Freezing
• Melting
• Boiling
• Evaporation
• Condensation

Note:

Þ   Pure substances are substances without any impurities added to it

Þ   Impurities are something that is not of the same substance. When a substance is mixes with an impurity, it is known as a mixture.

FREEZING

1. When water loses heat to its surroundings, its temperature drops.

2. When the temperature of water falls to 0^oC (or when water is cooled to 0^oC), liquid water changes to ice. This process is called freezing.

3. Freezing is a heat loss process.

4. When water changes from liquid to solid state, we say that it freezes.

5. The temperature at which a liquid freezes is called the freezing point. The freezing point of pure water is 0^oC. 

6. Freezing point = Melting point (only for all pure substances)

7. When water freezes, its volume increases, this makes ice less dense than water, causing ice to float.

8. Freezing point differs from one substance to another. Also, if there are impurities in the substance, the freezing point will be lower.
1. E.g. if sugar is added to water and the liquid is cooled, the freezing point of the ‘impure water’ is lowered to about -5^o C.

MELTING

1. When ice gains heat from its surroundings, it changes to the liquid state.

2. Melting is the process when a solid changes into a liquid.

3. The melting point of ice is 0^oC.

4. The melting point of pure substances is fixed.

5. The melting point of all substances is different from one another.

6. Melting points change when a substance is mixed with impurities.

7. The melting point will be lower if there are impurities in them, the greater the amount of impurities, the lower the melting point will be.

8. Hence melting points are very useful in determining the purity of a sample. Impure sample have lower melting points than pure solids.

BOILING

1. When we heat water to a temperature of 100^o C, many air bubbles form in the water. These bubbles contain water in the gaseous state, which will escape from the liquid water into the air around it.

2. At 100^o C, water changes from a liquid to a gas. This process is known as boiling.

3. The temperature at which a liquid boils is known as its boiling point.

4. The boiling point of pure water is 100^o C.

5. Under normal conditions, the highest temperature that pure water can reach is 100^o C. Any additional heat gained by the water after that is used to convert it into its gaseous state (steam). It’s temperature does not increase further.

6. The boiling point of a pure substance is fixed. However, boiling points differ from one substance to another.

7. Boiling points are changed when there are impurities in the substance.

8. The boiling point will be higher if there are impurities in them. The greater the amount of impurities, the higher the boiling point.

9. Air pressure also affects the boiling point.

1. The higher the pressure, the higher the boiling point. Water can boil at 120^o C to 130^o C in a pressure cooker.
2. The lower the pressure, the lower the boiling point. E.g. at the top of a very high mountain, water can boil at a temperature as low as 90^o C because of very low air pressure at high heights.

EVAPORATION

1. Evaporation is a process by which a liquid changes into gas.

2. Evaporation takes place all the time and at any temperature, even at very cold places like the North and South Pole.

3. Evaporation takes place when water changes to a gas below its boiling point.

4. During evaporation, a liquid absorbs heat from the surrounding. Hence, evaporation has a cooling effect. For example, our skin feels cooler when our sweat evaporated.

5. How slowly or quickly evaporation takes place is known as the rate of evaporation.

1. The rate of evaporation is HIGH if evaporation takes place quickly (ie things dry up faster)
2. The rate of evaporation is LOW if evaporation takes place slowly.

6. The rate of evaporation refers to how fast liquid water changes to water vapour.

7. The rate of evaporation depends on the following factors:

1. Temperature:

                                               i.     The higher the temperature, the faster the rate of evaporation.

                                             ii.     An increase in temperature causes water to evaporate faster.

                                            iii.     E.g. clothes dry very fast on a hot and sunny day.

2. Wind:

                                               i.     The stronger the wind, the faster the rate of evaporation.

                                             ii.     On a windy day, clothes dry faster.

3. Humidity:

                                               i.     Water evaporates faster when the air is less humid.

                                             ii.     Humidity is the amount of water vapour in the air.

Þ   High humidity means that there is a lot of water vapour in the air causing the air to be moist.

Þ   Low humidity means that there is less water vapour in the air, causing the air to be dry.

Þ   When the amount of water vapour in the air increases, humidity also increases.

Þ   When the amount of water vapour in the air decreases, the humidity also decreases.

                                            iii.     Singapore is very humid so our perspiration does not evaporate very quickly.

4. Exposed surface area:

                                               i.     The larger the exposed surface area, the faster the rate of evaporation.

                                             ii.     E.g. water in a large plate will evaporate faster than water in a small cup.

Evaporation versus Boiling

Characteristics	Evaporation	Boiling
When does it occur?	Occurs all the time and at any temperature.	Occurs only at a liquid’s boiling point.
Where does it occur?	Takes place ONLY at the liquid’s surface	Boiling can take place throughout the liquid.
Speed	Process of evaporation is very slow	Boiling happens very fast.

CONDENSATION

1. When water vapour or steam are cooled and loses heat, the gas becomes a liquid.

2. The change from the gaseous state to the liquid state is called condensation.

3. Water vapour condenses into liquid water whenever it touches a surface that is relatively cooler.

4. Examples of condensation in daily lives:

1. When a glass of ice water is left at room temperature, the water vapour in the surrounding air touches the cold outer surface of the glass and condenses into water droplets.
2. When you place a metal spoon over a kettle of boiling water, droplets of water can be seen on the spoon.
3. Dew form on the leaves of plants in the morning because condensation of water vapour into water droplets when they touch the cooler leaf surfaces.
4. Daddy’s spectacles turn misty when he steps out of a air conditioned car because water vapour from the surrounding condenses on the cold surface of the lens.
5. Sometimes, when the weather is very cold, the water vapour in the air condenses to form millions of tiny water droplets. The air becomes misty and unclear. This phenomenon is called a fog.

                                               i.     Fog: condensed water vapour in the air at or near ground level.

Mathematics

Speed:

            Speed= Distance/Time

            Distance= Speed x Time

            Time= Distance/Speed

Order of Operations:

1. Follows the BODMAS rule

-        Brackets

-        Orders

-        Division

-        Multiplication

-        Addition

-        Subtraction

English Words to Describe Your Behaviour #2

List of Words That Describe Behavior in Social Situations

Many things can affect behavior:

• Your mood
• The people that you are around
• Things that happen to you

Stress and your physical condition also have a bearing on your behavior. We are going to look at good, socially accepted behavior and bad or out of control behavior.

Here is a list of words that describe behavior that is good in social situations:

• Caring: desire to help people
• Charming: pleasant, delightful
• Considerate: thinking of others
• Enthusiastic: has strong feelings; ardent
• Excitable: gets excited easily
• Faithful: being loyal
• Funny: causing people to laugh
• Kind: thoughtful, caring
• Pleasant: polite
• Polite: exhibiting good manners
• Sincere: being totally honest
• Thoughtful: thinking things over 

For the opposite kind of behavior, here is a list of words that refer to bad social behavior:

• Aggressive: verbally or physically threatening
• Argumentative: often arguing with people
• Bossy: always telling people what to do
• Deceitful: doing or saying anything to get people to do what you want or to get what you want
• Domineering: constantly trying to control others
• Inconsiderate: not caring about others or their feelings
• Irritating: bothering people
• Manic: acting just a little crazy
• Manipulative: always trying to influences other people
• Moody: being unpredictable; changing moods often
• Rude: treating people badly; breaking social rules
• Spiteful: seeking revenge; hurting others because you didn’t get what you want
• Thoughtless: not thinking about the effects of your actions or words

Words That Describe Personal Behavior

The following words describe behavior that is more personal in nature. The behavior is not affected very much by the company or situation.

• Active: always busy with something
• Ambitious: strongly wants to succeed
• Assertive: being outgoing and confident
• Careless: not being careful; rushing into things
• Cautious: being very careful
• Conceited: thinks he is better than others; arrogant
• Conscientious: taking time to do things right
• Creative: someone who can make up things easily or think of new things
• Curious: always wanting to know things
• Docile: submissive, does what he is told
• Extroverted: very outgoing; confident
• Impulsive: saying or doing things without thinking first
• Introverted: keeps to himself, doesn’t share thoughts and feelings
• Inventive: thinks of new ideas
• Nervous: very uncomfortable
• Passive: does not argue; does as he is told
• Perfectionist: wants everything to be done right and perfectly
• Pragmatic always sees the practical side of things
• Reserved: keeps thoughts and feelings to himself
• Serious: no-nonsense kind of behavior
• Shy: quite and reserved; lacking in confidence
• Trustworthy: simply worthy of someone’s trust
• Volatile: changing moods very quickly

Maths-Algebra #2

• Laws of Exponents

  There are several different "laws" or properties when working with exponents:
  
  
  Next we'll look at a few formulas that can be used when working with polynomials.
  
  
  

  Polynomial Formulas

  There are special rules or formulas that can be used when multiplying polynomials or factoring polynomials. Let's take a look:
  

  Multiplying Polynomials Using FOIL

  To multiply two polynomials, multiply each term in the first polynomial by each term in the second polynomial. This is also known as using FOIL.
  

  

  
  
  
  

  Square of a Binomial

  To square a binomial, you add: the square of the first term, twice the product of the two terms, and the square of the last term. Take a look:
  

  

  
  
  
  
  
  

  Difference of Two Squares

  When two binomials differ only by the sign between their terms (one a plus, the other a minus), we call this a Difference of Two Squares.
  The rule is very easy to remember: Subtract the square of the second term from the square of the first term. Take a look:
  

  

  
  
  
  
  
  

  Polynomials - Special Factoring

  The following formulas will actually take our special products from above and work backwards to factor. Same rules, we are just working backwords to find the factors.
  
  

  Perfect Square Trinomial

  A perfect square trinomial results in binomial squares.
  If you notice that the first and last terms are perfect squares, then check to see if the trinomial factors as a binomial square.
  

  
  
  
  

  Difference of Two Squares

  
  
  
  

  The Sum and Difference of Two Cubes

  The following are the formulas for factoring the sum and difference of two cubes:
  
  
  
  
  
  

  Quadratic Formula

  There are two formulas that are associated with quadratic equations: the vertex formula and the quadratic formula.
  
  

  Vertex Formula

  The vertex formula is used when you must find the vertex (minimum or maximum point) of the parabola.
  

  
  
  
  

  Quadratic Formula

  You can use the quadratic formula to solve ANY quadratic equation. It is used most when the quadratic equation is non-factorable.
  

  

  
  
  
  
  
  Our last basic algebra formula is the Pythagorean Theorem.
  
  
  

  Pythagorean Theorem

  The Pythagorean Theorem is used to identify the length of the sides of any right triangle.
  
  

SCIENCE-Q&A

Why Do Cows Have Four Stomachs?

- A cow is a big animal that eats grass and other tough plants. It eats a large amount of food everyday. It needs four stomachs to break down and digest its food properly. Each of the four stomachs has a special job to do.

When a cow feeds on grass, it gives the grass a quick chew with its back teeth and swallows it. The partly chewed grass goes into the cow’s first stomach called the rumen. In side the rumen, the grass is broken down into ‘balls of cud’. When the rumen is full, the cow stops eating and rests. While it rests, the cow brings back each ball of cud into its mouth and chews it into a soft pulp. Then it swallows the pulp again.

The mushy pulp goes through the second and third stomachs where the harder bits of the pulp are filtered out. These tough bits go back to the rumen and the process starts all over again. The rest of the pulp goes on to the last stomach where it is completely digested.

The cow puts its food through many rounds of digestion and absorbs the nutrients at the end. This means that a cow is only healthy if all of its four stomachs are in good working order.

      

Why do Volcanoes Erupt?

-A Volcano can be a mountain or hill that has an opening at the top. The opening is called the vent and it leads deep down into the earth. When a volcano erupts, hot melted rock, gas and ash from inside the earth burst out through the vent.

Below the Earths surface crust is a layer called the mantle. The mantle is made up of melted or molten rocks called magma. The intense heat from the mantle forces the magma upward towards the Earths surface. The hot, runny magma squeezes along any crack or passage. A volcanic eruption occurs when magma shoots out through the vent of a volcano. The magma that shoots out is known as lava.

In every volcanic eruption, there is incredible heat. In some eruptions, however, the lava is much hotter that in others. If erupting lava is very hot, it flows down the side of the volcano like a liquid. It can flow for tens of kilometers before it cools into solid rock. If erupting lava is cooler, there may be explosions as lumps of lava together with volcanic ash are thrown high into the air. Volcanic ash may be blown far away from the erupting volcano by winds before it settles. It breaks down quickly and becomes fertile soil.

-A volcano may be active, dormant or extinct. An active volcano often erupts. A dormant volcano has not erupted for a long time. A extinct Volcano no longer erupts.

Why is Lightning seen before Thunder is Heard?

-When there is a thunderstorm, flashes of light are seen in the sky, and loud rumbles or bangs can be heard. The flashes of light are called lightning and the loud noises are called thunder.

Lightning is a huge electrical spark in the sky. It is caused by a build-up of electricity inside a thundercloud. Drops of water and crystals of ice whizz about and collide with each other inside the cloud. When they collide, they create a electrical force.

Eventually, the electrical force becomes very strong. The force becomes so strong that it jumps through the air to other clouds or down to the ground. As the electrical force jumps, sparks of lightning can be seen. The lightning heats up the air that it passes through. The air expands very fast and makes a sound like an explosion. The sound is called thunder.

Light travels very fast, at about 300,000 kilometres per second. Sound, however travels more slowly, at only 0.33 kilometre per second. This difference in speed is the reason why lightning is seen before thunder is heard.

Why do Rainbows appear when it is both Sunny and Raining at the same time?

-A rainbow is an arch of seven colours of light that is seen in the sky. Rainbows can usually be seen in the morning or afternoon, when it is about to rain, during the rain or after rain.

Sunshine consists of straight rays of light that reach the Earth from the Sun. Sunlight is called ’white light’. When the straight rays of white light bend, they separate into seven bands. Each band is a different colour and they are always in the same order: Red, Orange, Yellow, Green, Blue, Indigo and Violet.

When a ray of sunlight hits and enters a raindrop, the raindrop’s round surface bends the ray. The white light separates into seven colours and forms a tiny rainbow inside the raindrop.

Then, the mini rainbow is reflected from the back of the raindrop. It is bent again as it passes out through the curved surface of the raindrop.

The arched shape of a rainbow occurs because the rays of light are bent twice, once on the way in and once on the way out of each raindrop. This is why there must be both sunshine and raindrops at the same time to make a seven-coloured rainbow.

SYSTEMS

Circulatory System: The Circle of Blood

On average, your body has about 5 liters of blood continually traveling through it by way of the circulatory system. The heart, the lungs, and the blood vessels work together to form the circle part of the circulatory system. The pumping of the heart forces the blood on its journey.

The body's circulatory system really has three distinct parts:pulmonary circulation, coronary circulation, and systemic circulation. Or, the lungs (pulmonary), the heart (coronary), and the rest of the system (systemic). Each part must be working independently in order for them to all work together.

Respiratory System: Oxygen Delivery System

The primary function of the respiratory system is to supply the blood with oxygen in order for the blood to deliver oxygen to all parts of the body. The respiratory system does this through breathing. When we breathe, we inhale oxygen and exhale carbon dioxide. This exchange of gases is the respiratory system's means of getting oxygen to the blood.

Respiration is achieved through the mouth, nose, trachea, lungs, and diaphragm. Oxygen enters the respiratory system through the mouth and the nose. The oxygen then passes through the larynx (where speech sounds are produced) and the trachea which is a tube that enters the chest cavity. In the chest cavity, the trachea splits into two smaller tubes called the bronchi. Each bronchus then divides again forming the bronchial tubes. The bronchial tubes lead directly into the lungs where they divide into many smaller tubes which connect to tiny sacs called alveoli. The average adult's lungs contain about 600 million of these spongy, air-filled sacs that are surrounded by capillaries. The inhaled oxygen passes into the alveoli and then diffuses through the capillaries into the arterial blood. Meanwhile, the waste-rich blood from the veins releases its carbon dioxide into the alveoli. The carbon dioxide follows the same path out of the lungs when you exhale.

The diaphragm's job is to help pump the carbon dioxide out of the lungs and pull the oxygen into the lungs. The diaphragm is a sheet of muscles that lies across the bottom of the chest cavity. As the diaphragm contracts and relaxes, breathing takes place. When the diaphragm contracts, oxygen is pulled into the lungs. When the diaphragm relaxes, carbon dioxide is pumped out of the lungs.

Integumentary System: Cutting Dead Cells

The body's integumentary system supports the excretory system in the removal of waste. Skin, hair, fingernails and toenails make up the system by which surface level wastes are removed.

The skin protects the body and also provides for the removal of dead cells and sweat, which contains waste products. Hair, fingernails and toenails are actually accumulations of dead epidermal cells. As more cells die and need to be removed, the hair and nails grow.

Excretory System: Poison Protection

If you knew there was poison hidden in your house, you would surely do everything possible to find and remove that poison. If you didn't, you and your family would slowly die. How would you find it? How would you remove it? You would probably figure out a system of searching and removing. That would be an excretory system.

Your body does the same thing every day. Hidden throughout your body are dangerous poisons that must be removed in order for it to survive. The process of excretion involves finding and removing waste materials produced by the body.

The primary organs of excretion are the lungs, kidneys, and skin. Waste gases are carried by blood traveling through the veins to the lungs where respiration takes place. Dead cells and sweat are removed from the body through the skin which is part of theintegumentary system.

Liquid waste is removed from the body through the kidneys. Located beside the spine in your back within your ribcage, the kidneys are small (about 10 centimeters long) reddish-brown organs that are shaped like beans.

During circulation, blood passes through the kidneys in order to deposit used and unwanted water, minerals, and a nitrogen-rich molecule called urea. The kidneys filter the wastes from the blood, forming a liquid called urine. The kidneys funnel the urine into the bladder along two separate tubes called ureters. The bladder stores the urine until muscular contractions force the urine out of the body through the urethra. Each day, your kidneys produce about 1.5 liters of urine. All of it needs to be removed from your system. This occurs through urination.

If your kidneys are diseased and not working properly, the buildup of waste in your system will eventually lead to death. Some kidney diseases can be treated with medication. Severe kidney diseases require more intense treatment. One treatment is called dialysis. The patient's blood is pumped through a dialysis machine which filters the waste from the blood and returns the clean blood. A dialysis patient has to spend nearly sixty hours each week attached to the machine.

The most radical treatment for kidney disease is a kidney transplant. Healthy people can live comfortably with only one kidney. Therefore, their other kidney can be donated to a person with kidney disease. The donor and patient must have very similar genetic structures in order for the patient to accept the new kidney without complications. The patient also receives anti-rejection drugs. During a kidney transplant operation, the healthy kidney is placed in the abdomen of the patient and attached to the blood vessels and bladder. The patient's original kidneys are not removed.

The digestive system

The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. There are also two solid digestive organs, the liver and the pancreas, which produce juices that reach the intestine through small tubes. In addition, parts of other organ systems (for instance, nerves and blood) play a major role in the digestive system.

The Muscular system

The muscular system makes up nearly half the weight of the human body, this is why when we train we sometimes put on weight instead of losing it. We put on muscle weight.
The muscles provide the forces that enable the body to move. Muscles stretch across joints to link one bone with another and work in groups to respond to nerve impulses.

The skeletal system

Our skeleton is tough and flexible. It supports weight and protects our internal organs. Bone tissue stores minerals, such as calcium, and it is constantly renewed, which is how our bones are able to heal.
Bones are cleverly designed to allow movement at the joints and provide great stability. The bones provide alight but strong framework for the bodies soft tissues.
The number of bones in the human body actually varies from person to person but the average number is 206.

Science Human Facts

1. If stomachs did not have a lining of mucus, your stomach would digest itself.

2. There are 60,000 miles of blood vessels in the human body.

3. It takes about 60 seconds for a human blood cell to make a complete circuit of the body.

4. The average person will shed 40 pounds of skin in his/her lifetime.

5. 1/15th of a pint of blood is pumped with every heartbeat.

6. Humans share 98.4% of our DNA with chimps. In comparison, we share 70% of our DNA with a slug.

7. The lightest baby to survive weighed a mere 283 grams.

8. On average, women say 7,000 words per day while men manage just over 2,000 words.

9. The human brain uses 20% of the body’s energy but is only 2% of the body’s weight.

10. On average, humans lose 40-100 strands of hair per day.

11. A sneeze can exceed the speed of 100mph.

12. A cough can reach the speed of 60mph.

13. The average person will drink about 16,000 gallons of water in his/her lifetime.

14. It takes 17 muscles to smile while taking 43 muscles to frown.

15. The human brain is composed of 75% water.

16. Human thigh bones are stronger than concrete.

17. More germs are transferred while shaking hands compared to kissing.

18. There are approximately 550 hairs in a person’s eyebrow.

19. The strongest muscle in the human body is the tongue.

20. A person produces 10,000 gallons of saliva in an average lifetime.

21. The hardest bone in the human body is the jawbone.

22. The number of eye blinks varies greatly from about 29 blinks each minute if you are talking to someone to only 4 blinks each minute if you are reading.

23. The average human blinks 25 times per minute.

24. A nail takes around 6 months to grow from base to the tip.

25. Each second 10,000,000 cells die and are replaced in your body.

26. Your liver performs over 500 functions in your body.

27. The average person spends 1/3 of their lifetime sleeping.

28. More germs are transferred when shaking hands than kissing.

29. The average person (from western culture) consumes 10 liters of alcohol per year.

30. Roughly 75% of people who play the radio in their car sing along to it.

31. Human thigh bones are stronger than concrete.

32. Your right lung takes in more air than your left one does.

33. The human brain is composed of 75% water.

34. 70% of the composition of dust in your home is made up of shed human skin and hair.

35. The tooth is the only part of the human body that can’t repair itself.

36. One human hair can support 3kg.

37. Humans are the only animals that cry tears and blush.

38. It takes the interaction of 72 different muscles to produce human speech.

39. If the normal one hundred thousand hairs on a head were woven into a rope, it could support a weight of more than twelve tons.

40. The fingernail grows about 1.5 inches per year.

41. The total amount of skin covering an adult human weighs 6 lbs.

42. The average person flexes the joints in their fingers 24 million times during a lifetime.

43. Each person inhales about seven quarts of air every minute.

44. On average, we breathe between 12 and 18 times a minute.

45. The average guy will grow about 27 feet of hair out of his face during his lifetime.

46. Approximately 1 out of 25 people suffers from asthma.

47. The average man sweats 2 1/2 quarts every day.

48. One out of every hundred American citizens is color blind.

49. An average person laughs about 15 times a day.

50. A human heart beats 100,000 times a day.