Q&A - P4 Science

[ChiefKiasu]

Moderator's Note: Please use this thread to ask for help on specific questions. Please refrain from out of topic chatter in this thread to make it easier for the community to find the answers they need.

[zinc6539]

This is a question from Nan Hua Primary School CA2 2010 P4 Science. It's shown as question 9 on this website: http://www.oldschool.com.sg/index.php/module/PublicAccess/action/Wrapper/sid/9595afb87c8cf767f034c3ae53e74bae/coll_id/7288/recs_ppg/5/desc/Continual+Assessment+2+%28%232%29%3A+Section+B/pg_id/2


I hope to get some clarifications on the answer given. (a) Why did the plastic ruler gain heat when the question only states that Mary heated the iron ring. (b) & (c) Could there be an alternative answer that the ruler gets stuck in the ring, but did not break, since plastic ruler is slightly flexible?

[mother777]

zinc6539:

This is a question from Nan Hua Primary School CA2 2010 P4 Science. It's shown as question 9 on this website: http://www.oldschool.com.sg/index.php/module/PublicAccess/action/Wrapper/sid/9595afb87c8cf767f034c3ae53e74bae/coll_id/7288/recs_ppg/5/desc/Continual+Assessment+2+%28%232%29%3A+Section+B/pg_id/2


I hope to get some clarifications on the answer given. (a) Why did the plastic ruler gain heat when the question only states that Mary heated the iron ring. (b) & (c) Could there be an alternative answer that the ruler gets stuck in the ring, but did not break, since plastic ruler is slightly flexible?

Hi,

For (a) the reason for heat gain inthe ruler can be explained using the concept of conduction. The heat will move from the heated metal ring to the plastic due to the difference in temperature. As a result, both the metal ring and the plastic ruler will gain heat.

for b and c, yes the answer can be that the ruler will remain stuck with little bending or break based on the contraction in the metal ring.

if initially, the ring expanded a lot due to heat gain. then after loss of heat source it will contract back to its original position pressing on the plastic ruler. which may break if the contraction was large.

But if the initial expansion was just enough to force fit the ruler, then after contraction the ruler may just bend a little due to its flexible nature and stay fit inside the metal ring.

this is my understanding..

hope this helps

[usaik]

Hi,

Below is a question from one of the past year exam paper.
The answer provided is (1) D only.
http://i52.tinypic.com/34es178.jpg\">

I would like to check : Is the part which I have circled in red above not a leaf? And if is is a leaf, then shouldn't the answer be (2) instead of (1)?

Would appreciate some clarification into the above please. Thank you.

[Niedino]

usaik:

Hi,

Below is a question from one of the past year exam paper.
The answer provided is (1) D only.
http://i52.tinypic.com/34es178.jpg\">

I would like to check : Is the part which I have circled in red above not a leaf? And if is is a leaf, then shouldn't the answer be (2) instead of (1)?

Would appreciate some clarification into the above please. Thank you.

Hi usaik,

Yes, the part you circled is the leaf. However, as you can see in the diagram, it has not fully emerged and grown fully, hence, it is unable to photosynthesize. At that stage, the plant is still using food stored in the seed leaf to germinate. Hence, (1) D only is the correct answer.

Hope it helps!

Niedino

[Niedino]

zinc6539:

This is a question from Nan Hua Primary School CA2 2010 P4 Science. It's shown as question 9 on this website: http://www.oldschool.com.sg/index.php/module/PublicAccess/action/Wrapper/sid/9595afb87c8cf767f034c3ae53e74bae/coll_id/7288/recs_ppg/5/desc/Continual+Assessment+2+%28%232%29%3A+Section+B/pg_id/2


I hope to get some clarifications on the answer given. (a) Why did the plastic ruler gain heat when the question only states that Mary heated the iron ring. (b) & (c) Could there be an alternative answer that the ruler gets stuck in the ring, but did not break, since plastic ruler is slightly flexible?

Hi zinc6539,

For (a), the ruler will gain heat from the iron ring due to conductivity.

For (b) & (c), Yes, it is possible, and I would assume that if your child had written such an answer and explained the flexibility of the ruler, your child would have gotten at least a partial mark.

Hope it helps!

Niedino

[usaik]

Niedino:

Hi usaik,

Yes, the part you circled is the leaf. However, as you can see in the diagram, it has not fully emerged and grown fully, hence, it is unable to photosynthesize. At that stage, the plant is still using food stored in the seed leaf to germinate. Hence, (1) D only is the correct answer.

Hope it helps!

Niedino

Hi Niedino,
It certainly helps. Thank you so much!

[smartmummy]

http://i53.tinypic.com/ztwvo7.jpg\">

Hi all pls help me.
My son's answer for (b) was
substance Q has a definite shape but p doesnot.

How to answer for this qn?

[smartmummy]

http://i54.tinypic.com/207vud3.jpg\"> http://i56.tinypic.com/152by8j.jpg\">


i took two pictures cos of clearness.Thanks

[Niedino]

smartmummy:

http://i54.tinypic.com/207vud3.jpg\"> http://i56.tinypic.com/152by8j.jpg\">


i took two pictures cos of clearness.Thanks

Hi smartmummy,

I would say that your child needed to add in these words to get the full marks 'Substance Q ... does not have a definite shape' To do well for the Science exams, you need to convince your child to give the full answer. One common weakness is a false sense of security, where a child thinks that his/her answer is adequate when it is not. Remind your child to imagine that the marker does not know the answer and it is his job to explain clearly.

Hope it helps!

Niedino