Thursday, January 15, 2009

Learning reflection off curved playing a game!

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


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

Sunday, January 11, 2009

Thursday, January 8, 2009

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!

Wednesday, January 7, 2009

$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:)