Q&A - P4 Science

[usaik]

Hi,


I need help on the rationale behind why the answer is (3) for the below question.
If the answer is (3), the principle \"Air can be compressed\" does not apply to the balloon. So which principle explains and support the answer below. Thank you so much.

http://i42.tinypic.com/qdv.jpg\">

[tianzhu]

usaik:

Hi,

I need help on the rationale behind why the answer is (3) for the below question.
If the answer is (3), the principle \"Air can be compressed\" does not apply to the balloon. So which principle explains and support the answer below. Thank you so much.

Hi

Air has no definite volume; it takes the shape of the container. This means it can be compressed to occupy a smaller space. It also can expand to take up a bigger space.

A balloon is made of material which can be stretched.

When you blow air into the balloon, it’ll expand. As more air is blown into the balloon, its volume increases until it finally bursts.

The glass ball cannot be stretched when additional air is pumped into it. Hence the air is compressed.

The balloon can be stretched to accommodate the extra air, hence the air expands to take the shape of the stretched balloon.

Option (3) is correct.

Best wishes

[24by7_mum]

Setup A, the glass ball cannot be expanded. When the plunger is pushed, the 100 cm of air entering the glass ball is compressed into the 300 cm of space in the glass ball (note: gas does not have definite volume and can be compressed)


Setup B, the balloon can inflated. When the plunger is pushed, the 100 cm of air is pushed into the ballon causing it to inflate and since balloon can be inflate it will take up the additional 100cm of space (300 + 100)

I hope I am right …

Hope this helps.

[usaik]

Hi Tianzhu, 24by7_mum,


Noted on your explanation. Thanks for your reply!!

[24by7_mum]

usaik,


I am so glad u posted this question. I asked my ds and guess what she totally forgotten the concept (was explaining to her while replying this post).

[usaik]

24by7_mum:

usaik,


I am so glad u posted this question. I asked my ds and guess what she totally forgotten the concept (was explaining to her while replying this post).

Guess this is the beauty of this forum where we all benefit from such collaborative learning!

[usaik]

Hi,


I need help on the following question. The answer provided is (3). No doubt that the seeds in setup A will germinate as it has air, warmth and moisture, however in setup C, wouldn't the seed just rot away as there is just too much water. TIA.

http://i40.tinypic.com/2zf36sw.jpg\">

[24by7_mum]

Hi All,


The answer to the qns below is 1. DD and I thinks is none of the answer is correct. LOL both of us are flipping through guide book but none suggested that the answer is 1.

One function of a stem is to
(1) store food for the plant
(2) store oxygen in the plant
(3) take in dissolved mineral salt
(4) hold the plant firmly to the ground

[Raider]

I think the most likely answer is (1). There are plants that store starch(food) in the stem. One such plant is the potato.

[atutor2001]

usaik:

Hi,


I need help on the following question. The answer provided is (3). No doubt that the seeds in setup A will germinate as it has air, warmth and moisture, however in setup C, wouldn't the seed just rot away as there is just too much water. TIA.

http://i40.tinypic.com/2zf36sw.jpg\">

Seeds soaked in water will still germinate. Therefore, as long as it has germinated we should not be too concerned with whether the germinated seeds will rot after that since the question did not ask if it will grow into a plant.