jedamum:

discuss psle science http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=1727&start=0.

pls do a search before starting a thread.
TQ

My apologies. I was at Pg 12 of the link you mentioned, but i clicked on 'New Post' instead - this seems to be the incorrect option - I should probably click 'Quote' to any of the posts. Sorry about that.

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http://www.postimage.org/image.php?v=Pq1EkKm0

Hi there, I have another query on this question - it's from the PSLE 5 year series ...
The answer given is distance y will decrease.
Iron ring will be attracted to magnet , but gravitational force exerted by combined weight of the iron ring and magnet A is greater than that of magnet A alone, reducing the distance y.

My question is : How do you know the gravitationl force is greater than the magnetic force of repulsion (which causes distance y in the first place?)

Thanks in advance.

Hi,


thanks a lot !! for the colorful background picture too !!

tianzhu:

Hi
Hope this helps.
http://farm3.static.flickr.com/2454/3575392074_9a6a4cfa56_o.jpg\">

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Hi,
Can you help me to solve this question? (preferably non-algebra, if possible).
The answer given is 1/3.
Thanks in advance.

http://www.postimage.org/image.php?v=aVLOAnr

It's from Tao Nan SA1 2008 paper.

Thanks for the quick response

tianzhu:

Drdj:

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http://www.postimage.org/image.php?v=Pq12Ooo0

Hi, can you help me explain why the given answer is option (4)?
Thanks.

Hi
Let us recap

In PSLE science, students are not taught how to determine the polarity of an electromagnet. They learned that an electromagnet is made when you coil an electric wire a few times around a magnetic material.
Copper is a non magnetic material.(MPH PSLE Science Guide pg 64)
For magnets, like poles attract and unlike poles repel. (MPH PSLE Science Guide pg 66)

Consider (1) --- The bulb lights up as a closed circuit is formed. The magnet may move to the left if unlike poles are facing one another.
(1)is a logical answer.

Consider(2) ---The copper remains in the same position as it is non magnetic. The magnet may move to the right if like poles are facing one another.Hence (2) is also correct.

Consider (3) ---The magnet either moves to the left or right.B and C cannot happen at the same time.Therefore (3) is out.

Consider(4) ---For the same reason as (3), this option is also out.

Therfore option (1) and (2) are logical.Where is this question from?

It's from Tao Nan SA1 2008 paper.

Thanks for your quick response

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http://www.postimage.org/image.php?v=Pq12Ooo0

Hi, can you help me explain why the given answer is option (4)?
Thanks.