Friday, February 4, 2011

GP Essay : The language of mathematics is the perfect language. Do you agree?

This essay topic is not an easy one to write on.
A student of mine posed this topic to me as a friendly challenge which I was glad to take on.
I might not have done as great a job on this as I would have liked but this represents my best efforts.
I was not time constrained; I took about 4 hours to write this in two sittings.

Click here for the essay:
The language of mathematics is the perfect language. Do you agree?

Physics : Trebuchet

Built this trebuchet in 2009 in preparation of a science camp. Didn't get to use it, but still hope to do so in a camp sometime soon. Test fired it; needs refinements on the release mechanism.

Great demo for conversion of energy. Definitely quite fun to setup and fire. Use tennis balls as ammo, but ideally something heavier should be swung on this although safety concerns would kick in. I think water bombs make a good ammo too.

Physics : Chladni Patterns

Chladni patterns are a really cool way to visualize standing waves.

For more info on the man and the field he helped pioneer:
Ernst Chladni on Wikipedia
Cymatics on Wikipedia

I rigged a speaker to an amplifier and a frequency generator. The speaker was modified such that the cone directly drives a square metal plate. Yellow art sand was added and when certain frequencies were dialed into the frequency generator, the sand would quickly coalesce to form patterns.

More details on setup will be posted here. I'm still working on it at the moment.

Meanwhile, enjoy the pictures!



Thursday, February 3, 2011

GP Essay : Music has one purpose – to entertain

I wrote this GP essay some time ago for one of my students.
Makes for an interesting read; not the regular current affair GP essay question.

Click here for the essay:

Chem : Table of the Solubility of Ionic salts

Solubility List

Exceptions
All Sodium Salts are soluble
All Potassium Salts are soluble
All Amonnium are soluble
All Nitrates are soluble
These exceptions over-ride the solubility table below. A useful way of remembering this is to recall the word SPAN.

Solubility Table



Soluble Insoluble
Sulphates All soluble except Barium, Lead, Calcium, Silver, Mercury
Hydroxides Barium and calcium slightly soluble All other hydroxides insoluble
Carbonates
All insoluble
Chlorides All soluble except Silver, Lead, Mercury


Chem : Metal Reactivity list

'O' level Chem Metal Reactivity list with Hydrogen and Carbon.


Metal Reactivity list

Common Name Symbol Illustrative examples
Potassium

Sodium

Calcium

Magnesium
Burning Mg underwater
Aluminum
Aluminum Pots. Thermite. Napoleon III VIP Dinnerware
Carbon
The Blast Furnace
Zinc
Galvanized Roofing
Iron

Tin
The tin can
Lead
Plumbum
Hydrogen

Copper

Silver
Tarnish
Gold
Aqua Regis

Chem : Cation and Anion List

This is a list of cations and anions commonly encountered in 'O' Level Chemistry.


Common Cations


Name

Formula

Aluminum

Al+3

Ammonium

NH4+

Barium

Ba+2

Calcium

Ca+2

Copper(I)

Cu+

Copper(II)

Cu+2

Iron(II)

Fe+2

Iron(III)

Fe+3

Hydrogen

H+

Lead(II)

Pb+2

Magnesium

Mg+2

Potassium

K+

Silver

Ag+

Sodium

Na+

Zinc

Zn+2


Common Anions


Simple ions:

Fluoride

F-

Chloride

Cl-

Bromide

Br-

Iodide

I-

Oxide

O2-

Sulfide

S2-

Hydroxide

OH-

Phosphate

PO43-

Sulfate

SO42-

Nitrate

NO3-

Carbonate

CO32-

Dichromate

Cr2O72-

Permanganate

MnO4-


Q : Why the name Cations?

A : These ions are Positive in charge, and gather at the Cathode during electrolysis.


Q : Why the name Anions?

A : These ions are Negative in charge, and gather at the Anode during electrolysis.