Tutor Niedino: Pri Science Questions and Concepts

[kancheongmum]

Hi Niedino


Need confirmation on the following

A metal cup and a plastic cup both contain hot water of the same temperature. After 15 mins the water in which cup will have a higher temperature. Answer: water in the plastic cup Reason: metal is a better conductor of heat than plastic, so heat is conducted away faster.

What if the water is changed into cold water?
After 15 mins the water in which cup will have a lower temperature.
Answer: water in the plastic cup. Reason: metal is a better conductor of heat so it gain heat faster from the surrounding.

Thank you

[rkumar]

Correct on both accounts.

[rkumar]

Oops sorry, didn’t realise it was a private thread. please disregard previous post.

[singapore45]

kancheongmum:

Hi Niedino


Need confirmation on the following

A metal cup and a plastic cup both contain hot water of the same temperature. After 15 mins the water in which cup will have a higher temperature. Answer: water in the plastic cup Reason: metal is a better conductor of heat than plastic, so heat is conducted away faster.

What if the water is changed into cold water?
After 15 mins the water in which cup will have a lower temperature.
Answer: water in the plastic cup. Reason: metal is a better conductor of heat so it gain heat faster from the surrounding.

Thank you

Hi Niedino,

Could you provide the answer for this as I am a little confused about it as well. What should the proper phrasing be?

[rkumar]

kancheongmum:

Hi Niedino


Need confirmation on the following

A metal cup and a plastic cup both contain hot water of the same temperature. After 15 mins the water in which cup will have a higher temperature. Answer: water in the plastic cup Reason: metal is a better conductor of heat than plastic, so heat is conducted away faster.

What if the water is changed into cold water?
After 15 mins the water in which cup will have a lower temperature.
Answer: water in the plastic cup. Reason: metal is a better conductor of heat so it gain heat faster from the surrounding.

Thank you

Hi Niedino

Correct me if i am wrong but i think the reason for Q1 \"metal is a better conductor of heat than plastic, so heat is conducted away faster.\"
should be Metal is a poor insulator of heat so heat is lost to the surrounding faster

[lemofish]

Hi Niedino,


Can you recommend any good science revision and reference books available at Popular? My son is in P3. TIA.

[HaleyCopterz]

rkumar:

kancheongmum:

Hi Niedino


Need confirmation on the following

A metal cup and a plastic cup both contain hot water of the same temperature. After 15 mins the water in which cup will have a higher temperature. Answer: water in the plastic cup Reason: metal is a better conductor of heat than plastic, so heat is conducted away faster.

What if the water is changed into cold water?
After 15 mins the water in which cup will have a lower temperature.
Answer: water in the plastic cup. Reason: metal is a better conductor of heat so it gain heat faster from the surrounding.

Thank you

Hi Niedino

Correct me if i am wrong but i think the reason for Q1 \"metal is a better conductor of heat than plastic, so heat is conducted away faster.\"
should be Metal is a poor insulator of heat so heat is lost to the surrounding faster

Hi,

We do not say that a material is an 'insulator of heat' that would be marked wrong. Nothing is an insulator of heat as everything can conduct heat to a certain degree. So we should say that metal is a better conductor of heat than plastic. If a material is a better conductor of heat, that means heat travels through that material very quickly.

[BigDad]

HaleyCopterz:

rkumar:

[quote=\"kancheongmum\"]Hi Niedino


Need confirmation on the following

A metal cup and a plastic cup both contain hot water of the same temperature. After 15 mins the water in which cup will have a higher temperature. Answer: water in the plastic cup Reason: metal is a better conductor of heat than plastic, so heat is conducted away faster.

What if the water is changed into cold water?
After 15 mins the water in which cup will have a lower temperature.
Answer: water in the plastic cup. Reason: metal is a better conductor of heat so it gain heat faster from the surrounding.

Thank you

Hi Niedino

Correct me if i am wrong but i think the reason for Q1 \"metal is a better conductor of heat than plastic, so heat is conducted away faster.\"
should be Metal is a poor insulator of heat so heat is lost to the surrounding faster

Hi,

We do not say that a material is an 'insulator of heat' that would be marked wrong. Nothing is an insulator of heat as everything can conduct heat to a certain degree. So we should say that metal is a better conductor of heat than plastic. If a material is a better conductor of heat, that means heat travels through that material very quickly.[/quote]Hi HaleyCopterz,

So that means we cannot use the word 'insulator of heat'? :?

[Niedino]

kancheongmum:

Hi Niedino


Need confirmation on the following

A metal cup and a plastic cup both contain hot water of the same temperature. After 15 mins the water in which cup will have a higher temperature. Answer: water in the plastic cup Reason: metal is a better conductor of heat than plastic, so heat is conducted away faster.

What if the water is changed into cold water?
After 15 mins the water in which cup will have a lower temperature.
Answer: water in the plastic cup. Reason: metal is a better conductor of heat so it gain heat faster from the surrounding.

Thank you

Hi KCmum,

There's been quite a few replies to it. The answer you provided already makes sense, and the phrasing is quite good except for one problem, the reason is not in line with the answer. Another problem I foresee is that your child does not understand the true meaning of conductivity.

Perhaps you can run the experiment with him at home with a simple thermometer?

My answer to the question would be

a) the metal cup, as metal is a better conductor of heat than plastic, so the heat loss from the water is faster than the the plastic cup.

b) the plastic cup, plastic is a poorer conductor of heat, so less heat is lost to the surroundings as compared to the metal cup.

Always answer to the question and in this case, both questions deal with heat loss / gain. I would always recommend that the reason be given in line with the earlier answer (plastic cup --> plastic cup because) and (plastic cup --> metal is a better) so that your child will not be confused.

[rkumar]

HaleyCopterz:

rkumar:

[quote=\"kancheongmum\"]Hi Niedino


Hi Niedino

Correct me if i am wrong but i think the reason for Q1 \"metal is a better conductor of heat than plastic, so heat is conducted away faster.\"
should be Metal is a poor insulator of heat so heat is lost to the surrounding faster

Hi,

We do not say that a material is an 'insulator of heat' that would be marked wrong. Nothing is an insulator of heat as everything can conduct heat to a certain degree. So we should say that metal is a better conductor of heat than plastic. If a material is a better conductor of heat, that means heat travels through that material very quickly.

[/quote]Hi Haleycopter and Bigdad

insulator of heat is indeed a valid term. Poor conductors of heat are good insulators of heat and vice versa. i believe it is still covered in the \"o\" level syllabus. \"Plastic\" heat properties question came out 2004 'O' level physics exam. Good Insulator/poor conductor both accepted.:D

I think you may have mistaken insulation to mean stop heat altogether.

definition i found on a website

Substances that do not conduct heat well are called insulators. The word insulator comes from the Latin word insula, which means island. Insulators have a low coefficient of conductivity; they do not conduct heat well. Nonmetals, such as wood, textiles, and plastic, are usually poor conductors. Gases are also poor conductors.