Alright! I can tell by your tone of voice that you are feeling really upset about this. Stay focused on the last 2 papers. Rest assured that we still have time to mend it before the real SPM exams.

Upload the papers here and I can help to check in my recess time.

As long as we are human beings (using heuristic approach to solve problem), we susceptible to human errors, and that's how we explore and learn. In contrast, algorithmic approach (following step-by-step) always yield to correct solution within the boundary conditions, but it cannot learn or solve problems beyond the boundary. As a robotics enthusiast, our mission is to develop hybrid computational intelligence systems in a robot to enable it to learn and reason about how to behave in response to complex goals in a complex world.

Thanks for the uploads. I re-compile them (Questions only) in pdf format for easy viewing.

 Paper_1.pdf ( 904.83k ) Number of downloads: 65


 Paper_2.pdf ( 748.01k ) Number of downloads: 32

Your method



My method



4 steps, 4 marks, equally short.

Give me some time, as I have other works as well! By the way, you can also invite Krevaki, p3nguin and Intermission.

Most likely the same Kerja Kursus Matematik Tambahan (Selangor) I received and uploaded the sample answer for Logarithm Project in Post #829.

To put it exactly, you are doing the basic technique of Separation of variables, in which algebra allows you to rewrite a Differential Equation so that each of two variables occurs on a different side of the equation.

Sorry R.xim, I don't quite get your question. Can you help me to understand your true question with the diagrams below?

To answer your question in simple words, your eyes indeed see the wavefronts. Because your eyes will respond to wavelengths from about 390 to 700 nm, you see the wavefronts in the forms of colors.



However your brain does not interpret light as wave because the wavelengths of the visible spectrum is much smaller than the smallest thing you can see. Experts believe that the naked normal eye can see objects as small as about 0.1 millimeters. To put this in perspective, the tiniest things a human being can usually see with the naked eye are things like human hair and lice.

To put it exactly, the “rays” you described is actually wavefronts, but the wavelengths of visible light are too small for our brain to perceive as having wave-like behavior. However, the wave-like behavior of light can be observed through polarization and diffraction experiments.

Visible light is a kind of electromagnetic radiation in the form of energy emitted which exhibits wave-like behavior as it travels through space. Electromagnetic radiation does not have physical shape. Thus, our eyes cannot see light in physical manifestation. Instead, we see colors when light travels through space. However, phenomena such as the Photoelectric effect and the Compton effect offer ironclad evidence that when light and matter interact, the light behaves as if it were composed of particles having energy hf and momentum h/l.



The end result is that we must accept both models and admit that the true nature of light is not describable in terms of any single classical picture. In other words, the particle model and the wave model of light complement each other.



This post has been edited by Critical_Fallacy: May 27 2013, 03:28 PM

Put it precisely, the resistance of the bulb is constant for all 4 cases. The question says so ... indirectly. Can you spot it?

At SPM level, nothing more detailed than understanding the electrical principles Series and Parallel circuits.





From the bulb, 12V @ 24W, we can determine R = 6Ω and I = 2A.

Since Case A & B are out of discussion as highlighted by work_tgr, testing above parameters in Case D shows that 24W is delivered to the Bulb.

Very good! Please continue to share good stuffs here or B.U.M.P. this link to help the students, especially those weak at Elementary Algebra.

Newton’s second law for a system of particles states that the net external force on a system of particles equals the total mass of the system multiplied by the acceleration of the center of mass.

So, Newton’s 2nd law gives you

Σm*a = Σf = N

(mx + my)*a = fx + fy

Therefore, for Block Y

my*a = fy

where

a = N / (mx + my)

P.S. It should be mentioned that the horizontal surface is frictionless, not just smooth only.

Can you give a working example of that?

Assumption: All five filament bulbs are designed to operate on the fixed voltage (V). The brightness of the bulb depends on the power delivered to the filament (P = I²R), which depends mainly on the resistance of the filament. Therefore, our interest is the resistance of the filament that depends primarily on two factors: material it is made of, and its shape.

(1) Filament Material
Copper has higher electrical conductivity than Tungsten. Thus, Copper is a better conductor, and the current would pass through the filament without dissipating much energy, which means nothing would light up. Moreover, copper has lower young's modulus than tungsten, which means it will easily break.

(2) Filament Thickness
By R = ρl/A, a thick tungsten filament has lower resistance than an otherwise identical thin tungsten filament.

(3) Filament Length
Similarly, by R = ρl/A, a straight tungsten filament has lower resistance than an otherwise longer coiled tungsten filament.

(4) Inert Gas Pressure
The main cause of the failure of bulb is the evaporation of tungsten, which causes weak spots in the filament. By PV = nRT, the pressure is proportional to the temperature. As the temperature is raised, the filament evaporation rate rises. The inert gas also has the cooling effect.

Conclusion: To produce the brightest light among five, the characteristics of the bulb have to be (1) tungsten filament, (2) thin filament, (3) coiled filament, and (4) low pressure inert gas. And Bulb R has all these features.

EDIT: Please refer to Post #899.

This post has been edited by Critical_Fallacy: May 31 2013, 04:23 PM

By Newtonian mechanics, the mass (m) of the trolley remains unchanged.

constant Force (F) → constant acceleration (a)

constant acceleration → the velocity (v) is increasing linearly

Since the kinetic energy E ∝ v², therefore the graph should be parabolic. Answer: (A)

P.S. Graph C is a damping harmonic response, specifically the overdamped case. The function of this graph is typically f(t) = c*[1 - e^-(σt)], where σ is the resonant angular frequency and c is the steady-state value.

I don't run the experiment to verity that but your point is valid. I made mistakes on Post #894 because I was misled by the marking scheme, and you probably should consider making a experimental validation. It is generally true that the brightness of a light bulb is a function of its filaments. For a given voltage of operation, a less resistive filament will draw more current, run hotter and will glow more brightly, as to say getting more incandescent.

Consider the following power rating of two bulbs:

(1) 120V 60W Bulb: The ideal filament resistance must be R = (120V)² / 60W = 240Ω. The measured rms current shall be approximately I = 60W / 120V = 0.5A.

(2) 120V 100W Bulb: The ideal filament resistance must be R = (120V)² / 100W = 144Ω. The measured rms current shall be approximately I = 100W / 120V = 0.8333A.

For more info, read this article  Basic_Physics_of_the_Incandescent_Lamp.pdf ( 268.68k ) Number of downloads: 4
, and study the experiment on the last page.

I'm afraid I'm reaching my limit in physics knowledge because I don't conduct inert gas experiment with gas-filled bulbs. Perhaps you can find more information in the following webpages:

(1) Operating Principle

(2) Gas Filling Effects

(3) Filament Coiling Effects

Is there any problem?

Sure! From here >> Sila muat turun bahan di sini >> Bahan Matematik Tambahan 2013

Really? Maybe someone has “borrowed” my work. You can trace the date/time when it first appeared online. By the way, how's the progress of your project?