Q&A - P3 Science

[teh_oh]

atutor2001:

teh_oh:

Hi atutor2001,
Thanks for the information.
But can you please explain again why the answer state that 'Brass Fixture' has been placed in the wrong category if it is non-magnetic?
Thank you.

Hi teh_oh

I need to clarify on whether were the magnetic materials being printed in the question as 1 single group or were they being broken up into 2 groups, namely : iron & nickel placed together and the steel screw being placed separately, under a different column. If it is so, then (3) is correct as the main-classification is \"magnetic & non-magnetic\". The items are then sub-classified into \"Element (consist of 1 type of metal)\" and \"Alloy (mixture of metals)\".

However, if all the magnetic materials are presented in the chart as a single group (column), then there is something wrong with the question.

Hi atutor2001,
The steel screw is placed in the same group as iron and nickel under magnetic metals. There is no mention on 'alloys' in the question. Then seems like something wrong with this question :D. Phew. Thank you.

[atutor2001]

teh_oh:

Why didn't that surface of the iron tank that is in contact with the magnet, have temporary magnetism through 'induction' (as in the first diagram) to attract the steel ball bearing?

Why nowadays no respond one?

Anyway, you are correct that the \"ENTIRE\" surface of the iron tank will become a temporary magnet due to induction. However, it has very weak magnetic force. The magnetic force from the small bar magnet is used to re-align all the \"little magnets\" in the tank (to north-south direction). With such a large tank, the magnetic force cannot completely re-align all the \"little magnets\" in the tank. Many of the \"little magnets\" in the tank are still not aligned and so the magnetic force of the tank is weak.

If we use a \"super\" strong magnet, the steel ball bearing will be stuck to the surface of the iron tank.

[Nebbermind]

children holiday, parents also holiday mah!! :imcool:

[pingathot]

Hi parents, m shocked to c the questions asked abt magnet 'cos for P4 they’ve not taught yet. U meant u parents have already get your children to do the papers in advance? Oh mine, then I must b lacking bhind.

[cimman]

pingathot:

Hi parents, m shocked to c the questions asked abt magnet 'cos for P4 they've not taught yet. U meant u parents have already get your children to do the papers in advance? Oh mine, then I must b lacking bhind.

I think different schools cover different topics for SA1. My child's school has already covered magnets for SA1 for P4.

[Niedino]

pingathot:

Hi parents, m shocked to c the questions asked abt magnet 'cos for P4 they've not taught yet. U meant u parents have already get your children to do the papers in advance? Oh mine, then I must b lacking bhind.

Hi pingathot,

Different schools will adopt a different sequence to the teaching of the Science topics. The only fixed topic is Diversity, which is taught at the beginning of P3. The rest of the topics are modular and can be taught seperately from each other. There is no prescribed sequence.

Hope it helps!

[pingathot]

Oh I see! Thank you u all.

[Happy Mama]

pingathot:

Hi parents, m shocked to c the questions asked abt magnet 'cos for P4 they've not taught yet. U meant u parents have already get your children to do the papers in advance? Oh mine, then I must b lacking bhind.

Yes I think different schools cover differently. My Pri 3 DD will be covering Magnets in Term 4 this year.

[teh_oh]

atutor2001:

teh_oh:

Why didn't that surface of the iron tank that is in contact with the magnet, have temporary magnetism through 'induction' (as in the first diagram) to attract the steel ball bearing?

Why nowadays no respond one?

Anyway, you are correct that the \"ENTIRE\" surface of the iron tank will become a temporary magnet due to induction. However, it has very weak magnetic force. The magnetic force from the small bar magnet is used to re-align all the \"little magnets\" in the tank (to north-south direction). With such a large tank, the magnetic force cannot completely re-align all the \"little magnets\" in the tank. Many of the \"little magnets\" in the tank are still not aligned and so the magnetic force of the tank is weak.

If we use a \"super\" strong magnet, the steel ball bearing will be stuck to the surface of the iron tank.

Hi atutor2001,
Thank you for the explanation.

[teh_oh]

Hi,

Relating to magnets again, I need to know if the guide/assessment book is wrong or our concept is wrong:-
http://i56.tinypic.com/xpuhk3.jpg\">
The above is from a guide book.
Are the poles wrongly stated? Compare to the diagram in
http://www.le.ac.uk/se/centres/sci/selfstudy/mam9.htm
the poles stated in the guidebook is different.
Based on single-stroke method, during stroking, when the North-pole of the magnet when lifted off the head of the nail, the polarity of that nail at the head should be South.
Am I right?

http://i54.tinypic.com/2r779qt.jpg\">
The above is taken from an assessment book by the same publisher of the guide in the first picture.
The above question answer key is 3. Correct or wrong?

Thank you.
(We have given up seeking info from the science teacher because the teacher's replies had been 'go and check the internet', 'have i taught this already/before?' and when asked if key words or answering technique will be taught,'everything is taught in class. students who pay attention should know.')