Physics Form 4: Chapter 2 - Hooke's Law

• Elasticity is the ability of a material to return to its original shape/length when the stretching force or the compressing force is no longer acting on it.
•  Hooke’s law states that the force applied is proportional to the extension of spring,  provided the elastic limit is not exceeded.

Gradient = spring constant 

Area under the graph = elastic potential energy

• Spring constant quantifies the stiffness of a spring.
• Steeper gradient of graph F against x, extension has a stiffer spring.
• Spring A is stiffer than spring B.

Physics Form 5: Chapter 3 - Moving Coil Meter

Moving coil meter only measures direct current. It has a linear scale because the pointer deflection is directly proportional to the size of the current.

How moving coil meter works:

1.  With the switch open, there is no current flow  through  the meter coil.

2.   With no current flowing, the coil generates no magnetic field and the pointer stays at zero reading.

3.  Close the switch and a current flows through the coil.

4.  The current creates a catapult magnetic field and a turning force acts on the coil.

5.  The turning force rotates the coil and the pointer deflects across the scale until the hairspring produces an equal and opposing turning force on the coil.

As the current through the coil increases, the magnetic field generated around the coil increases. The stronger the magnetic field, the larger the turning force of the coil to move the pointer.

 Function of the hairspring: 

With the use of hairsprings, the coil will return to its initial position when there is no current. The springs will also tend to resist the movement of the coil when there is current through the coil. When the attraction between the magnetic fields (from the permanent magnet and the coil) is exactly equal to the force of the hairsprings, the coil will stop moving toward the magnet. 

Other features are used to increase the accuracy and sensitivity of this meter movement such as. 

• An iron core is placed inside the coil to concentrate the magnetic fields. 
• Curved pole pieces are attached to the magnet to produce a radial magnetic field to ensure that the turning force on the coil increases steadily as the current increases. 
• Using stronger magnet.
• Increasing the number of turns in the coil.
• Increasing the area of the coil.
• Using a weaker hairspring.

Methodists to open private schools as public standards fall

The Malaysian Insider news

KUALA LUMPUR, May 29 — The Methodist Church in Malaysia believes private schools are a solution to the declining academic standards in public schools, and have begun building them in areas where there is an absence of government schools. The Methodist Church, together with other Christian denominations, has been involved in education since the 1800s when the British first came to the Malay Peninsula. The Church has 26 secondary and 42 primary schools assisted by the government, six private schools and a private college.

Bishop Dr Hwa Yung said the Methodist Church’s mission now was to build a “string of private schools” so that Malaysian youth would have the best possible education. “We have now also begun building private schools which seek to contribute towards raising academic standards in this country, something which unfortunately seems to have gone into freefall in the last few decades,” Yung said in his foreword of the Methodist Boys’ School Penang’s 120th anniversary souvenir programme.

The Penang school celebrated its anniversary yesterday in a dinner attended by Penang Chief Minister Lim Guan Eng. Hwa Yung lamented the fact that most mission schools were now under government control and run according to policies which were not too “sympathetic” to this category of schools. However, he said the Methodist Church had begun setting up schools for rural folks who have no access to government schools, and that one of these “private schools” has been recognised by the local education department and its students have been allowed to sit for year six and form three exams.

“We are seeking more human and financial resources to begin work in other areas of special needs, whether they be poverty, physical or developmental disabilities,” the bishop added. According to the Church, its sixth-form college, the Methodist College here, is aspiring to reach university college status by the next decade.

Physics Form 4: Chapter 2 - Principle of Conservation of Energy

• The principle of conservation of energy shows that energy cannot be created or destroyed but can change from one form to another.
• The principle of conservation of energy states that the total quantity of energy in an enclosed system is always the same.
  

For example:  Energy transformation on a roller coaster

• At the top of the hill, the cars possess the maximum quantity of potential energy. Potential energy  is dependent upon the mass of the object and the height of the object. The car's large quantity of potential energy is due to the fact that they are elevated to a large height above the ground. 

• As the cars descend the first drop, they lose much of this potential energy in accord with their loss of height. The cars subsequently gain kinetic energy. Kinetic energy is dependent upon the mass of the object and the speed of the object. 

• The train of coaster cars speeds up as they lose height. Thus, their original potential energy (due to their large height) is transformed into kinetic energy (revealed by their high speeds). As the ride continues, the train of cars are continuously losing and gaining height. 

• Each gain in height corresponds to the loss of speed as kinetic energy (due to speed) is transformed into potential energy (due to height). Each loss in height corresponds to a gain of speed as potential energy (due to height) is transformed into kinetic energy (due to speed).

Conclusion:

1. Potential energy convert to kinetic energy and vice versa
2. Total energy in the system is still the same.

Chemistry Form 4: Chapter 5 - Electrical Conductivity of Ionic Compound

In solid state, ionic compound does not conduct electricity. It is because there is no freely moving ions in solid state. The negative ions and positive ions are strongly held together by electrostatic forces in a crystal lattice structure as shown below:

But, when ionic compound is heated up until its boiling point, the sufficient heat energy able to break up the strong electrostatic forces between positive ions and negative ions. This causes negative ions and positive ions to move freely in molten state. Thus, ionic compound can conduct electricity in molten state.

When ionic compound dissolves in water, the crystal lattice structure collapses and thus releases positive ions and negative ions. This causes negative ions and positive ions to move freely in aqueous state to conduct electricity.

Click on the diagram below to play!

Physics Form 4: Resolving Forces Into Components

Addition of vector 

Click on the diagram below to play!

Click on the diagram below to play!

Any force can be resolved into the addition of two mutually perpendicular forces which are called components of force. The components of force are resolved along the x-axis = horizontal component and the y-axis = vertical component.

 

For example:

 

Come Back to Penang, Overseas Students Told

The Star, Friday 20 May 2011
PENANGITES studying overseas should return home after they have completed their studies since Penang is going to be the most happening place in Malaysia with many “exciting” projects.Chief Minister Lim Guan Eng said the graduates could contribute their expertise to make the state an intelligent and international city.

“We want Penang to be your ideal home and we need you to make it happen,” he said at the presentation of excellence awards to 64 students who achieved excellent results in the STPM examination last year. A total of 70 awards, including six special awards, were given to the students who scored a Cumulative Grade Point Average (CGPA) of 4.0.

The students were from eight schools on Penang island and nine schools on the mainland. Lim said there was a great improvement in the results as 42 students received the awards in 2009 and 41 students the year before. The students each received a certificate and RM400 for each award

Physics Form 5: Chapter 3 - Alternating Current Motor

• The permanent magnets used have curved surfaces at its poles to create a radial magnetic field which has a uniform strength.
• The uniform magnetic field ensures that the force acting on the rectangular coil is uniform.
• A pair of slip rings is used to ensure that the rotation of the rectangular coil is always in the same direction

Click on the diagram below to play!

Chemistry Form 4: Chapter 5 - Lewis Dot Structure of Covalent Compound

Lewis structures are diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule. A Lewis structure can be drawn for any covalently bonded molecule, as well as coordination compounds. They are similar to electron dot diagrams in that the valence electrons in lone pairs are represented as dots, but they also contain lines to represent shared pairs in a chemical bond (single, double, triple, etc.).

Lewis structures show each atom and its position in the structure of the molecule using its chemical symbol. Lines are drawn between atoms that are bonded to one another (pairs of dots can be used instead of lines). Excess electrons that form lone pairs are represented as pairs of dots, and are placed next to the atoms.

Click on the diagram below to play!

Physics Form 5: Chapter 2 - Problem Solving of Series and Parallel Circuit

Ohm's law states that the current flowing, I through a metal conductor is directly proportional the potential difference, V across the conductor if the temperature remain constant.

By using Ohm's law equation V = I R, we can solve calculation questions in series and parallel circuit. For example:

Click on the diagram below to play!

Penang People Geng

After Jimmy Choo, Nicol David, Lee Chong Wei and others who make Penang state proud at global stage, now we have another Penang-lang in Britain who become the first non-English mayor. Continue to read her story in today The Star newspaper below:

Courtesy from The Star, Tuesday  17 May 2011

PETALING JAYA: A woman who was born and raised in Penang, will take oath tomorrow to be the first non-English mayor in England. Helen Chuah, who loves her curry mee, will be taking the badge and robes of the mayor's office of the city of Colchester in a ceremony held at the city's Moot Hall.

“I feel very honoured and privileged to be elected as the first non-English mayor of this historic town of Britain, and would wish to foster closer ties between Colchester and Malaysia,” she told The Star yesterday. “There are many Malaysian students in the University of Essex here and together with the Malaysian media presenters based in London, we hope to promote Malaysian culture, food and possible business links as well,” Chuah, 61.

Chuah, who was a student at St George's Girls' School in Penang, left to train as a nurse in Britain in 1971. “I applied to train as a nurse in England and I promised myself that I will go to the first hospital that accepts me and that turned out to be Severalls Hospital in Colchester,” she said.

She entered public office as a councillor in 1998. For the past year, she was Colchester Council's deputy mayor.“My one regret is that my late parents will not be here to witness this ceremony. I know they would feel proud and that I have not let them down,” she added.

Chuah is married to Englishman Mike Hogg, who is also a Colchester councillor. They have a daughter Rachael Choo, who is a teacher in London. The family regularly returns to Malaysia for holidays and to meet with friends and family. Colchester is located about 100km north-east of London.

Chemistry Form 4: Chapter 5 - Covalent Bond

Covalent bonds are formed when one or more electron pairs are shared between non-metallic atoms to form a molecule in order to achieve a stable duplet or octet electron arrangements of noble gas.

 How covalent bond is formed in carbon dioxide:

• Atom oxygen has 6 valence electrons and 2.6 electron arrangement.
• Each atom oxygen needs 2 more electrons to fill the valence shell in order to achieve a stable octet electron arrangement. Hence, each atom oxygen contributes 2 electrons for sharing.
• Atom carbon has 4 valence electrons and 2.4 electron arrangement.
• Each atom carbon needs 4 more electrons to fill the valence shell in order to achieve a stable octet electron arrangement. Hence, each atom carbon contributes 4 electrons for sharing.
• One atom carbon shares 4 electrons with two atom oxygen to achieve a stable octet electron arrangement. 

Some examples of covalent bond:

Types of covalent bond:

Physics Form 4: Chapter 2 - Safety Car Features

According to the Newton's First Law, a moving object will continue moving in a straight line unless external force acted on it. As a result, if you are sitting on braking car, you will keep on moving and been thrown out of the seat due to inertia effect.

 

Impulsive force is produced during collision according to the Newton's Second Law. If time of impact is reduced, the greater the impulsive force produced causing severe damage to the car.

In making a car safer to drive, engineers have to overcome these two factors that are inertia effect and impulsive force. Here are some safety features incorporated in a car:

1. Safety belt - help to hold the passengers in their position during collision to prevent them from being thrown forward due to inertia.
2. Front and rear crumple zone - easily crushed to increase the time of impact.
3. Shatter-proof windscreen - it will not break into pieces easily.
4. Airbags - to increase the time of impact and to cushion the driver from being hitting the front of the car.
5. Passenger safety case - reinforced to protect passenger.
6. Collapsible steering - to increase the time of collision if the driver crashes against it.
7. ABS braking system - to prevent the car from skidding if sudden brake is applied.
8. Headrests - prevent the passengers from suffering severe neck injury.
9. Padded dashboard - increases time interval of collision so that impulsive force is reduced.

Chemistry Form 4: Chapter 4 - Periodic Table

• Elements in the periodic table are arranged in periods (row) and groups (column).
• Groups include having the same electron arrangement in their outermost shell, which results in group elements sharing similar chemical properties.
• The electrons in the outermost shell is termed valence electrons.
• Valence electrons determine the chemical properties of the element and participate in chemical bonding.

Physics Form 5: Chapter 1 - Properties of Wave

• Amplitude, A  is the maximum displacement of a particle from the equilibrium position. The amplitude is a measure of energy carried by the wave. The higher the wave energy, the higher the amplitude.
• Wavelength is the distance between two adjacent crests or troughs.
• Period, T  is the time taken for a complete oscillation of a particle of a wave.

• Frequency, f  is the number of complete oscillations performed by a particle of a wave in one second.

Chemistry Form 4: Chapter 5 - Ionic Bond

• Ionic bonds are formed when valence electrons are transferred from a metal atom to a non-metal atom.
• Metal atom releases valence electron to form positive ion in order to achieve stable noble gas octet electron arrangement.
• Non-metal atom gains valence electron to form negative ion in order to achieve stable noble gas octet electron arrangement.
• Positive ions and negative ions are held strongly by electrostatic force.

Click on the diagram below to play!

Physics Form 5: Chapter 3 - Electromagnetic Induction

• Electromagnetic induction is the production of an electromagnetic force, (e.m.f)   in a conductor by changing magnetic field.

• Each time the straight wire cuts across the magnetic field or the permanent magnet moves towards the solenoid, a current is induced in the coil and a deflection is observed in the sensitive galvanometer.
• An induced e.m.f  is produced in a conductor if the conductor is in a changing magnetic field.

Faraday's Law states that the magnitude of the e.m.f induced in a conductor is directly proportional to the rate of change of the magnetic field.

Click on the diagram below to play!

Lenz’s law states that the induced current always flows in the direction in such a way that it opposes the change that produces it.

• When the S pole of a magnet moves towards end of a solenoid, the end will become a magnetic S pole to oppose the motion of the magnet.
• When the N pole is pulled away from end of the solenoid, the end will become a magnetic S pole so as to oppose the motion of the magnet.
• Lenz’s law is based on the principle of conservation of energy. The work done in moving the magnet is converted to electrical energy.

Click on the diagram below to play!

Physics Form 4: Chapter 2 - Forces in Equilibrium

• If an object is at equilibrium, then the forces are balanced which means that resultant force is zero. According to F = ma, the object's acceleration also zero when force in equilibrium achieved.

An object at equilibrium is either ...

• at rest and staying at rest, or
• in motion and continuing in motion with the same speed and direction.

  

Object at equilibrium position. The load is static.

Force A = 3.4 N  at an angle of 161 degree

Force B = 9.2 N at an angle of 70 degree

Force C = 9.8 N at an angle of 270 degree

A triangle of forces diagram showing forces are in equilibrium

Tribute to MUM

As time goes,

we grow up everyday 

When we reach adulthood,

our beloved mother has grown old

How many more years can we still celebrate Mother's Day for ours MUM...........

Honour your parent everyday!

PSD scholarships for SPM top scorers

The Star, Friday 6 May 2011
PETALING JAYA: The Cabinet has decided that all students who scored 8A+ and above in the Sijil Pelajaran Malaysia (SPM) 2010 will get a Public Service Department (PSD) scholarship. MCA deputy president Datuk Seri Liow Tiong Lai said Prime Minister Datuk Seri Najib Tun Razak was very happy with the SPM results and wanted to reward more good students.“We want to train more people and encourage good students further,'' he said, when contacted by The Star.

Yesterday, Deputy Education Minister Datuk Dr Wee Ka Siong also tweeted about the good news decided by the Cabinet on Wednesday. In his tweets, he said that such a move was commendable. “Indeed (the) Cabinet is adopting (a) colour-blind policy and (is) sincere in helping top students of all races,” Dr Wee said.
However, he could not be contacted for further comment.In July last year, Prime Minister Datuk Seri Najib Tun Razak said all students who scored 9A+ or more would receive PSD scholarships regardless of their race.

Najib added it did not matter if they were Malay, Chinese, Indian, Kadazan, Iban or others, adding that as long as they scored 9A+, they would get the scholarship, either for local or overseas studies.
He said this was to show that 1Malaysia was not just a slogan. During the announcement of the analysis of the SPM 2010 results in March, Education director-general Datuk Abd Ghafar Mahmud said this year's SPM results have so far been the best in four years.

He said a total of 403 candidates comprising 363 from government schools and 40 from private schools or private students obtained A+ (super distinction) in all subjects last year compared with 214 in 2009.
Abd Ghafar said this was the second year the ministry had used the new grading system with students graded according to A+, A, A-, B+, B, C+, C, D, E and G as compared with the previous standards where the grades were from 1A to 9G. This method gives a detailed breakdown of candidates who obtained grade A in the examination, he added.

10 Things to Learn From Japanese

1. THE CALM
Not a single visual of chest-beating or wild grief. Sorrow itself has been elevated.
 

2. THE DIGNITY
Disciplined queues for water and groceries. Not a rough word or a crude gesture.
 

 
3. THE ABILITY
The incredible architects, for instance. Buildings swayed but didn't fall.
 

4. THE GRACE
People bought only what they needed for the present, so everybody could get something.
 
5. THE ORDER
No looting in shops. No honking and no overtaking on the roads. Just understanding.
 

6. THE SACRIFICE
Fifty workers stayed back to pump sea water in the N-reactors. How will they ever be repaid?
   
7. THE TENDERNESS
Restaurants cut prices. An unguarded ATM is left alone. The strong cared for the weak.
 
8. THE TRAINING
The old and the children, everyone knew exactly what to do. And they did just that.
 
9. THE MEDIA
They showed magnificent restraint in the bulletins. No silly reporters. Only calm reportage.
 
10. THE CONSCIENCE
When the power went off in a store, people put things back on the shelves and left quietly. 

But, do not learn from this stupid Berita Harian's cartoon to make fun of others when Japanese peoples are in time of grief.