Q&A - P4 Science

[Super.049652kiasu]

Hi All,

Do your have any questions? I am quite good at science.

[mrswongtuition]

Do you mean that the balloon is submerged in the half-filled basin of water?

If yes, then when air is blown into the tube, the balloon fills up with air, pushing the water level in the basin higher. This is due to air in the balloon occupying space and displacing the water.

Regards,
Mrs Wong

[smartmummy]

need help

Study the experimental set-up in the figure below. What will happen to the paper clip after the switch is closed for some time?
http://i43.tinypic.com/34o96bt.jpg\">
1.The paper clip will be attracted to the copper rod.
2. The paper clip will be repelled by the copper rod.
3. The paper clip will rotate about.
4. Nothing will happen.

[jedamum]

smartmummy:

need help

Study the experimental set-up in the figure below. What will happen to the paper clip after the switch is closed for some time?
http://i43.tinypic.com/34o96bt.jpg\">
1.The paper clip will be attracted to the copper rod.
2. The paper clip will be repelled by the copper rod.
3. The paper clip will rotate about.
4. Nothing will happen.

4. Nothing will happen.

[smartmummy]

My son qn is,the picture shows switched off. If switched on it attracked the clip then switched off it will fall down.

No anwer like that. So just closed for a while of course nothing will happen.
Thanks jedamum.

[cherinelee]

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

Really helpful. Thanks.

[teh_oh]

Dear parents,


Appreciate your help in the following two questions regarding Matter.

Air occupies space and has indefinite volume, hence it takes up the shape of its container (indefinite shape)

Question 1: 100cm3 of air is pumped into a flattened football which can hold up to a capacity of 300cm3. How much air is inside the football after the air is pumped into it?

Question 2: 100cm3 of air is pumped into a sealed flask which has vacuum inside. How much air is inside the flask after the air is pumped into it?

Thank you. I do not have any answers as these questions were posted to me by my child.

[smartmummy]

These type of qns, how much capacity the container can hold is the volume of air. Doesn't matter how much we pumped into the container.

1)300cm3
2) didn't mention the sealed flask's capacity?

teh_oh:

Dear parents,

Appreciate your help in the following two questions regarding Matter.

Air occupies space and has indefinite volume, hence it takes up the shape of its container (indefinite shape)

Question 1: 100cm3 of air is pumped into a flattened football which can hold up to a capacity of 300cm3. How much air is inside the football after the air is pumped into it?

Question 2: 100cm3 of air is pumped into a sealed flask which has vacuum inside. How much air is inside the flask after the air is pumped into it?

Thank you. I do not have any answers as these questions were posted to me by my child.

[serenasgreenhouse]

smartmummy:

need help

Study the experimental set-up in the figure below. What will happen to the paper clip after the switch is closed for some time?
http://i43.tinypic.com/34o96bt.jpg\">
1.The paper clip will be attracted to the copper rod.
2. The paper clip will be repelled by the copper rod.
3. The paper clip will rotate about.
4. Nothing will happen.

Hi, smartymummy.

Answer is 4.

Explanation:
Copper is non-magnetic. Hence the copper rod cannot become an electromagnet to attract the clip.

[Charnic]

Pls urgently advise if wind a matter ? If not, why ?