Sunday, February 27, 2011

Physics Form 4: Chapter 2 - Newton First Law of Motion (Inertia)

  • Inertia is the tendency of an object to remain in its state of rest or of uniform motion in a straight line.
  • Law of inertia is also known as Newton's First Law of Motion
  • Newton's First Law of Motion state that an object will in its state of rest or of uniform motion in a straight line unless it is acted upon by a net external force.
Examples of effect of inertia:

When the cardboard is jerked quickly, the coin will fall into the glass.
Explanation:
  • The inertia of the coin resists the change of its initial state, which is stationary.
  • As a result, the coin does not move with the cardboard and falls into the glass because of gravity. 


Pull slowly - Thread A will snap.
Explanation:

  • Tension of thread A is higher than string B.
  • Tension at A = Weight of the load + Pulling Force

Yank quickly - Thread B will snap.
Explanation:
  • The inertia of the load prevents the force from being transmitted to thread A, hence causing thread B to snap.
For further examples, click on the diagram below to play!







Saturday, February 26, 2011

Physics Form 5: Chapter 1 - Electromagnetic Wave

An electromagnetic wave consists of vibration perpendicular of magnetic and electric fields.
Properties of electromagnetic wave:
  • They can transfer energy from one point to another.
  • They are transverse wave
  • They can travel through vacuum
  • They travel at the same speed of the light
  • They can be polarised
  • They all show reflection, refraction, interference and diffraction

Click on the diagram below to play!

Wednesday, February 23, 2011

Electrical Knowledge: Did You Know ??

Someone e-mail to me about electrical usage at house. Just want to share with you all. Anyway, have you forgotten how to calculate electricity bill ?

Here is a simple example to help you calculate electricity consumption. Let's assume you have one 100watt light bulb switched on for one hour. This will consume 100 watts per hour or 0.1 kilowatt hours (a kilowatt being 1000 watts). If you had ten 100watt light bulbs switched on for one hour your consumption would therefore be 10 x 100watts = 1000watts which is 1 kWh. You could then look at your electrical suppliers rate per unit (kWh) and see what the actual costs incurred are.

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Do you know what contributes to your monthly electricity bill?
For those in Semenanjung Malaysia, TNB’s tariff is approximately 30 sen to 45 sen per kilowatt-hour (kWh), depending on your usage. The more you use, the more expensive the rates!
 
Below is a short table of common electrical appliances, and a rough estimate on how much they cost to run for every hour.


(The cost may seem low, but remember, even using 3 sen/hour means that you will be paying about RM 20 a month if you leave it on for 24 hours a day!)


Appliance
Estimated cost (sen/hour)
Fluorescent lights
1 sen
Wireless Router
1 sen
ASTRO decoder + dish
2 sen
Table Fan
2 sen
Incandescent lights
3 sen
Ceiling Fan
3 sen
Computer (laptop)
5 sen
CRT (‘normal’) TV (21 inch)
3 sen
LCD TV (32 inch)
7 sen
Computer (desktop)
9 sen
Plasma TV (42 inch)
10 sen
Washing Machine
15 sen
Vaccuum Cleaner
17 sen
Electrical Clothes Iron
33 sen
Electric Hot Plate
46 sen
Air Conditioning
46 sen
Electric Water Kettle
50 sen

Sunday, February 20, 2011

Science Form 3: Chapter 3 - Haemodialysis

Haemodialysis is a method for removing waste product such as urea and water from blood when the kidneys are in the renal failure.



Click on the diagram below to play!

Chemistry Form 5: Chapter 1 - Catalyst Affects the Rate of Reaction

Catalyst is a chemical substance that change the rate of chemical reaction.

Characteristics of catalyst:
  • Catalyst remains chemically unchanged during reaction. Its chemical composition still the same before and after reaction.
  • Catalyst only change the rate of reaction.
  • Catalyst does not change the quantity of the product formed.
  • Catalyst is specific in its action.
  • Only a small amount of catalyst is needed to achieve a big increase in rate of reaction.
 How catalyst increase the rate of reaction:
  • When a positive catalyst is used in a chemical reaction, it enables the reaction to occur through an alternative path which requires lower activation energy.
  • As a result, more colliding particles are able to overcome the lower activation energy.
  • This causes the frequency of effective collision to increase.
  • Hence, the rate of reaction increases.
Decomposition of hydrogen peroxide by catalyst of manganese (IV) oxide

Thursday, February 17, 2011

Physics Form 4: Chapter 2 - Ticker Timer


  • A ticker timer consists an electrical vibrator which vibrates 50 times per second.
  • One tick is equal to the 1/50 = 0.02 ssecond
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Constant Velocity
 
  •  The distance between the dots are equally distributed.
  • All lengths of tape are equal length.







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Uniform Acceleration
  • The distance between the dots increases uniformly.
  • The length of strips of tape increases uniformly.
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Uniform Deceleration

  • The distance between the dots decreases uniformly.
  • The length of strips of tape decreases uniformly.

Saturday, February 12, 2011

Chemistry Form 4: Chapter 3 - The Mole

  • A mole is the quantity of anything that has the same number of particles found in 12.000 grams of carbon-12. That number of particles is Avogadro's Number, which is roughly 6.02x1023
  • A mole of carbon atoms is 6.02x1023 carbon atoms.




Physics Form 5: Chapter 1 - Interference of Waves

  1. Interference is the effect of superposition of two waves from two coherent sources.
  2. Coherent waves are the waves that can produce same frequency, same amplitude and same phase ( or with constant phase difference ).
  3. The  principle of superposition states that when two waves meet at the same point, the resultant displacement at that point is equal to the vector sum of the displacements produced by the individual waves at that point.
  • The constructive interference occurs when two crests or two troughs meet each other.
    • The destructive interference occurs when a crest meets a trough.
    • Anti-nodal line is a line joining all the constructive interference points 
    • Nodal line is a line joining all the destructive interference points




                      Click on the diagram below to play!

                      Wednesday, February 9, 2011

                      Facebook gaining popularity becoming suicide note

                      MALACCA: Seventeen-year-old Sally Lee Qian Chun (pic) posted disturbing online comments several days ago about wanting to end her life.

                      Yesterday morning, her classmates at SMK Seri Kota in Ayer Leleh watched in horror as she fell from the second floor of the school and died from head injuries. In the 9.15am tragedy, Sally Lee Qian Chun, a Form 5 student, abruptly walked out during the Chemistry lesson in the laboratory on the first floor and went to her classroom a floor above.

                      On Sunday night, at around 11.07pm, Lee lamented on her Facebook of a failed relationship and broken promises while reiterating her desire to take her own life. Her remarks drew some taunts and dares from her online friends. Some commentators even asked her to go ahead with what she wanted to do. In her last posting at 3.45pm on Monday, Lee reminded her friends to keep their promises of buying her a teddy bear and coffin. She also told them not to miss her when she was gone and to take care of themselves

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                      Last December, a 22-year-old man, Alviss Kong took his own life after another failed relationship. He posted, also on Facebook, a 45-minute countdown to his suicide. The youth jumped from the 14th floor of an apartment block in Cheras.

                      It was reported that the man became depressed after his girlfriend of four months broke up with him.

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                      Depression have become number one disease in the world. Loneliness and emptiness surrounding our heart, leads us to make a foolish decision. Committing suicide is the only way to solve problems in nowadays generation. The devil has succeeded his plan. Do you know that committing suicide is a sinful act? You have to pay a hefty price eternally for doing suicide.

                      I pray to the Lord that my student will not succumb to this idea of commit suicide whenever they meet unsolved problems. I pray that they will seek HIM, my wonderful teacher to get divine help. Nothing is impossible in God's eyes. Seek HIM faithfully and you will not thirsty again. Your heart is full of joy and peace. Believe me!......If not, try HIM.

                      Wednesday, February 2, 2011

                      GONG XI GONG XI 2011

                      WISH YOU:  A BLESSED HAPPY CHINESE NEW YEAR


                      Physics Form 5: Chapter 1 - Diffraction

                      1. Diffraction is the spreading of a wave as it goes through a narrow gap or passes round a small obstacle.
                      2. The effect of diffraction increases when the width of the gap is decreased.
                      3. The effect of diffraction increases when the wavelength is increased.

                      Application of diffraction in sea waves



                        Click on the diagram below to play!
                         

                        Tuesday, February 1, 2011

                        Another Malaysian Make It Again in World Stage , Jess Lee

                        PETALING JAYA: Jess Lee Kar Wei made Malaysia proud by winning the seventh season of Taiwan’s wildly popular singing competition reality TV show One Million Star (also known as Superstar Avenue) on Sunday night. The homegrown vocal powerhouse, who once declared ‘Malaysia boleh! Saya boleh!’ during the competition is One Million Star’s first Malaysian champion. Her win entitles her to a cash prize of NT1mil (RM100,000) and a recording contract with Warner Music Group.

                        The third in a family of four girls, Lee started singing and taking vocal lessons at age eight. The 22-year-old Seremban-born lass was one of two Malaysians who made it to the final six and went on to set a record for scoring full marks four times consecutively in the final round of competition. Apart from singing English songs like What’s Up? and Beyonce’s Listen, Lee even introduced Taiwan’s audiences to a Malay song, Gemilang. Her final winning song Hui Jia (Going Home by Shunza) brought tears to One Million Star judge Kay Huang who declared that Lee was ready for the international stage.

                        She entered Malaysian Idol's first season in 2004, fumbled badly at auditions, but was still invited back to perform at the finals with a reverberating Kaulah Segala Nya. That was 7 years ago. She did improve when she entered Astro Star Quest in 2008. The never say die, but keep learning attitude kept her going, and she made it after 7 years .... and she is still just 22. Now she has a recording contract with Warner Music Group.

                        Failure doesn't mean you are going to fail forever, instead failure makes you stronger and wiser