Video - Moments and an application in daily life

Don't mind the dirty fingers. Enjoy.

Sec 2 Camp 2009 @ MOE Changi Coast Adventure Campsite

18-20 Feb 2009

Download photos from here

I had fun! Hope you guys learn much from the experience!

Photos of a fond farewell

Goodbye Fazlin, all the best in your new school!

Learning reflection off curved surface...by playing a game!

A free, Flash-based game that may let you learn how does the Law of Reflection apply to curve surface....as well visualising attractive and repulsive forces. Introducing Gravity Pod 2!

Link: http://www.wickedpissahgames.com/games/gravitypods/GravityPods2.html

The screen shot shows how I can deflect the bullet using 2 curved surface as 'mirrors'.

Electromagnetic Spectrum - Some fascinating X-rays

Link from http://news.aol.com/health/article/woman-says-doctors-left-knife-in-head/298929

Even more fascinating is that all of the patients actually survived.

Journey to a Black Hole

It seems a lot of you are very curious about the stars, galaxy and the mysterious black hole, especially when I discussed about the speed of light. Here's an excellent interactive site that you can 'play' with to explore not one but two black holes!

To start your journey, go to http://hubblesite.org/discoveries/black_holes/

$30 = $29?!?!?!

Three men dine in a restaurant. The total bill is $30 and each man hands the waiter $10. Later, the cashier realises that there has been a mistake and the actual bill is $25. The waiter returns the change of $5. Since it's hard to distribute $5 among the three people, the three men decided to give the waiter a $2 tip and each men got back $1 change.

This means that each man has paid $9, making it a total of $27. Including the $2 tip, the 3 men has paid in total $29. But didn't they pay $30 in the first place? Where has that $1 gone to?!?!

Try and explain this. The first correct answer to reach my email will get a small prize!

Update 08 Jan 2009 9:22pm: Thanks for all your participation! After 1 day, one of my Sec 2 student has emailed me with a correct and reasonable explanation. To see her answer, select the blank space below with your mouse cursor.

Well, in the first place if 3 men paid $9, it becomes $27. FROM THE
$27, $2 already has been paid as a tip! Why do we have to then add $2 yet
again!. For example, from the $30 we remove $25, leaving us with $5. that $5 had
$2 as a tip. so we add $2 to $25, isn't that $27? and $27 divided by 3 is $9!
Each man paid $9! So, basically, you all have confused yourselves, by adding
another $2 to $27 when it already has been there, and the remaining $3 was the
change given to them:)

Reflection - size of mirror and image

3D drawing software - Google Sketchup

Found this rather interesting (and free) software: Google Sketchup. Interesting because it enables you to draw in 3 dimension as well as manipulate it around to give you views from different angle.

Perfect for those who have trouble visualising 3D trigonometry problems.

Test your English

Take the test at http://www.helloquizzy.com/tests/the-commonly-confused-words-test.

Here's my result:

Your result for The Commonly Confused Words Test...

Advanced

You scored 93% Beginner, 100% Intermediate, 100% Advanced, and 73%
Expert!

You have an extremely good understanding of beginner, intermediate, and
advanced level commonly confused English words, getting at least 75% of each of
these three levels' questions correct. This is an exceptional score.
Remember, these are commonly confused English words, which means most
people don't use them properly. You got an extremely respectable score.

Thank you so much for taking my test. I hope you enjoyed it!

For the complete Answer Key, visit my blog:
http://shortredhead78.blogspot.com/.

Take The Commonly Confused Words Test at HelloQuizzy

A 'simple' maths problem

A teddy bear has a cost price of $18, and a selling price of $21. One day, a young man decided to buy that bear and gave the shopkeeper a $100 dollar bill.

Unfortunately, the shopkeeper do not have $100 change. Hence he went to change the $100 bill into smaller change from a passer-by and gave the change to the young man.

After some time, the passer-by realise the $100 is a fake and demanded his money back from the shopkeeper! The shopkeeper has no choice but to return $100 to the passer-by.

Question: how much exactly did the shopkeeper lost?

Teacher's Day 2008 'rewards'

Thanks for all the gift!

Egg in a bottle experiment

Make your own balance toy

I have came across an interesting wooden balance toy, usually found in the markets of Vietnam and Thailand. Unfortunately, I lost mine and this is the only similiar picture I can find online:

However, you could make your own balance toy by simply using a piece of cardboard!

Step 1 - Download the picture (click on it and download the full size).

Step 2 - Print the shape on a piece of carboard and cut out the shape.

Step 3 - Bend at the lines to create this:

There you have it! Now watch as it does a seemingly impossible act by balancing on the tip of a pen.

Questions to ponder:

1. Is the toy considered stable?



2. Where do you think is the CG of the toy?



3. Do you think the toy is able to balance if you do not let the 'wings' droop down?

Ans: (highlight the space below with your cursor)

1. Yes, because the toy returns to its original position after being tilted.



2. The C.G. is below the tip (pivot), along the line of gravity pull.



3. No. This is because moving the wings upwards will cause the C.G. to move upwards, resulting in an unstable equilibrium. I.e. the moments created by the weight of the toy when the C.G. is above the pivot will tend to topple it. When the C.G. is below the pivot, the moments created by the weight will tend to move the toy back to the original position.

My posting

I realise I haven't update that I've been posted to Kranji Secondary school. You can find out more from their website: http://www.kranjisec.moe.edu.sg/ A beginning teacher is a very busy person...



Sorry Shuqunites, I did request to go back but I guess Shuqun do not lack Physics teacher. Still, all the best for your 'O's! If you need help just let me know.