Q&A - P3 Science

[Muffins]

elkniwt:

Hello,


Need help for Qn 27 in the following NanHua paper,
http://www.orlesson.org/orp/09Sc/P4-09-Sc-SA2-NanHua.pdf

Ans in ans key is (4)

May I know how come the clothes hanger will tilt. Is there any increase in mass on expansion?

Thanks.

Hi.

The clothes hanger will tilt because the metal rod, as heated, expanded in mass, so it is heavier than before, thus tilting.

[elkniwt]

Dear Muffins,


Thanks for your quick reply. But the problem is that my dd is taught in school that there is no change in mass when the object expands or contracts. When I surf the web for answers, I got a mixture of yes and no. Some sites say mass will increase, some say remain the same. :? Confused.

Muffins:

Hi.

The clothes hanger will tilt because the metal rod, as heated, expanded in mass, so it is heavier than before, thus tilting.

[Tang]

Muffins:

elkniwt:

Hello,


Need help for Qn 27 in the following NanHua paper,
http://www.orlesson.org/orp/09Sc/P4-09-Sc-SA2-NanHua.pdf

Ans in ans key is (4)

May I know how come the clothes hanger will tilt. Is there any increase in mass on expansion?

Thanks.

Hi.

The clothes hanger will tilt because the metal rod, as heated, expanded in mass, so it is heavier than before, thus tilting.

Hi,

Mass is the amount of matter in the object. As heating will not change the amount of matter in the object, so the mass does not change with heating.

For the question, the answer is (4).

The cloth hanger tilted downwards at the wooden block (not metal block) because the air below the metal block when heated up, expanded and rose, pushing the metal block upwards.

[elkniwt]

Hi Tang,


I got it. Thanks a lot!!

Regards.

Tang:

Hi,

Mass is the amount of matter in the object. As heating will not change the amount of matter in the object, so the mass does not change with heating.

For the question, the answer is (4).

The cloth hanger tilted downwards at the wooden block (not metal block) because the air below the metal block when heated up, expanded and rose, pushing the metal block upwards.

[elkniwt]

Hi,


For Qn 6 of this paper,
http://www.orlesson.org/orp/09Sc/P4-09-Sc-SA2-NanChiau.pdf

My question is plants are considered living things and they CAN move on their own, right?? [Plants cannot move from one place to another but they can move on their own, right?] Not so sure. Someone please help clarify my \"fogginess\". :?:

Thought the answer should be 3 but the ans in answer key is 4.

Thanks.

[atutor2001]

elkniwt:

.....


Thought the answer should be 3 but the ans in answer key is 4.

Thanks.

You are correct.

[peggy]

hi,


You’re right. Though plants can move towards sunlight but unlike animals where they can move from places to places.
So, the answer 4 is correct.

[the kiasu student]

elkniwt:

Hi,


For Qn 6 of this paper,
http://www.orlesson.org/orp/09Sc/P4-09-Sc-SA2-NanChiau.pdf

My question is plants are considered living things and they CAN move on their own, right?? [Plants cannot move from one place to another but they can move on their own, right?] Not so sure. Someone please help clarify my \"fogginess\". :?:

Thought the answer should be 3 but the ans in answer key is 4.

Thanks.

Plants can move but cannot move freely. Animals can move freely. you can also say plants \"move slowly\" but \"not moving freely\" is a more scientific phrase and is what you should use in an exam.

[match3frog]

P4 Question:


A picture showing 3 plastic bags tied at the top. Bag A is the smallest in size, Bag B is bigger than Bag A and Bag C is the biggest.

Q: Air is trapped inside the 3 plastic bags, A B and C.

Which of the following about the bags of air is definitely true?
1) The air in C is the most compressed
2) The air in the three bags has definite shape
3) The mass of air in B is bigger than that in A and smaller than that in C
4) The volume of air in B is bigger than that in A and smaller than that in C.

Answer is 4.
Can I know why the 3rd answer if not true? Won’t a bigger bag contain more air and therefore has a bigger mass than a smaller one?

Thanks!

[JayneLL]

match3frog:

P4 Question:


A picture showing 3 plastic bags tied at the top. Bag A is the smallest in size, Bag B is bigger than Bag A and Bag C is the biggest.

Q: Air is trapped inside the 3 plastic bags, A B and C.

Which of the following about the bags of air is definitely true?
1) The air in C is the most compressed
2) The air in the three bags has definite shape
3) The mass of air in B is bigger than that in A and smaller than that in C
4) The volume of air in B is bigger than that in A and smaller than that in C.

Answer is 4.
Can I know why the 3rd answer if not true? Won't a bigger bag contain more air and therefore has a bigger mass than a smaller one?

Thanks!

The options are very confusing..I am also confused when I read them, may I know where you got this question from? I better train my son these kind of questions before his SA2 exam. - Oops sorry I did not see carefully that these are P4 questions..I am actually looking for P3 qns, but anyway, could you let me know where you get these questions.