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!

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!

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

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

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.

Science Form Three: Chapter 3 - Kidney Function

Click on the diagram below to play!

Formation of kidney stone

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.