Q&A - P4 Science

[usaik]

Hi,


I need help with the following question. The answer provided is (3). Could someone kindly advise me why is it (3)? Why isn't the answer (4) as copper would be a better conductor of heat and henceforth will burn the paper as oppose to wood which is a poor conduct of heat?

http://i56.tinypic.com/289l8vk.jpg\">

Many thanks in advance.

[tianzhu]

usaik:

Hi,


I need help with the following question. The answer provided is (3). Could someone kindly advise me why is it (3)? Why isn't the answer (4) as copper would be a better conductor of heat and henceforth will burn the paper as oppose to wood which is a poor conduct of heat?

Hi

Option (3) is correct.

Copper is a better conductor than wood.

The paper around the wooden part is found to be charred but the paper around the copper rod does not burn. This is because heat is conducted away from the paper by the copper rod and the paper never gets hot enough to burn.

Best wishes

[usaik]

tianzhu:

Hi

Option (3) is correct.

Copper is a better conductor than wood.

The paper around the wooden part is found to be charred but the paper around the copper rod does not burn. This is because heat is conducted away from the paper by the copper rod and the paper never gets hot enough to burn.

Best wishes

Hi tianzhu,
It all makes sense now. Appreciate it! :thankyou:

[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.

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