Did any one went to the QtPS swimming carnival last Saturday? I thought it was rather nice. I also got to see the new Principal and vice-Principal for the first time.


I gotta say, QtPS is very fortunate to have these current leaders.

Bakugan:

:idea: I think it really reflects badly on the school when the Principal is the one \"undermining\" the contribution and efforts of his/her staff by telling the parents to hire their own tutors for their children. :x


Is he/she insinuating that the teachers are not capable of helping and guiding their students or he/she is not willing to help?

Either way, it speaks volume abt the Principal's management of the school itself :?

ps. I agree. Sleeping habits are vital...

I think it got something to do with the parents that send the kids to the top school. Most would be more \"keen\" (understatement maybe) for their kids to do well. Hence, they are probably more likely and can afford to send their kids to grilling centres. When it becomes a norm for most of the kids in these schools, the school actually don't need to do much.

My boss's son was also in another top school. Same situation and he did quite badly and quite demoralised.

Entry into \"top\" schools are not based on student's abilities, but rather, the parents \"abilities\". So I always felt these schools are over-rated.

mjl:

glchua:

My sister's kids went to one of a top primary school. When her kids didn't do well, the principal called her up, not to discuss how to help her kids, but to tell her to get them tutors.

I don't know what are school teachers for, if parents are told to get tutors if the kids can't cope in school. There is such thing as remedial class, for weaker students!

hi glchua, what are your sons' CCAs? My daughter is in Maths Club.

Sorry for the late reply. Was very busy.

My son is in WeiQi, my daughter is in Chinese dance.

Yeah, I personally don’t feel that top schools are really as hyped. It is easy to push the students (and thus the parents) but not easy to teach.


My sister’s kids went to one of a top primary school. When her kids didn’t do well, the principal called her up, not to discuss how to help her kids, but to tell her to get them tutors.

tianzhu:

glchua:

Not true. Water needs a lot of heat to increase 1 degree of temperature. Compared with iron, it is about 10 times more! Energy required to pull the orderly molecules from a solid state to a messy and energetic liquid state is very high too.

Hi

Thank you for your view. I am trying to look at this question from the concepts on heat learned in P4.

What would our primary kids think when they first read this question? Formula such as Q =mass x specific heat x temperature difference, specific heat capacities of water and iron and latent heat of fusion are not taught yet.

In Q26, one has to compare the heat gained by the water from the hot iron as compared to the heat gained by the melting cube of ice, bearing in mind that the beaker of water has greater mass than the cube of ice.
Primary students learn that heat flows from a higher region to a lower region. Hence, in applying this principle, a bigger temperature difference, greater heat gain for the water in the beaker(option 2).

This is how I would have answered this question. Of course my answer may not be right.

Best wishes

I apologize if I offended. My calculations may not be right too, since these stuffs are learnt long ago and I don't use these knowledge in my current line of work, not frequently anyway.

The issue here is not the answer. The original question from the school is wrong. One can't assume that all students see things in the limited light of what the teacher had taught. So it boils down to learning for giving correct answers, or learning to get closer to the truth.

Students who knew a little bit more through parents, internet, reading, etc would give a wrong answer or would get confused. If answers require careful phrasing (as some previous post had suggested), then teachers should do so too.

For any plucked fruit, physiological processes are still happening. A banana still ripens, mangoes give off heat if you encase it. An apple is thus still living.


If a dismembered plant is immediately considered dead, then grafting is not possible as a farming technique.

This is also true of dismembered parts of an animal. The tissue is still alive.

The apple is considered dead when it starts to rot. Respiration ceases, defense ceases, and microbes take over.

Sorry, just my opinion.

My son is out! Don’t know if any from his school got in. Congrats to all who got selected!

tianzhu:

As for Q26, based on what that has been learned in P4 science, heat flows from a hotter object to a colder object. A greater difference in temperature, therefore greater heat gain.

Best wishes

Not true. Water needs a lot of heat to increase 1 degree of temperature. Compared with iron, it is about 10 times more! Energy required to pull the orderly molecules from a solid state to a messy and energetic liquid state is very high too.

Tang:

Extracted postings from cbox.

http://www.wendykoh.com/08/primary5-chijca1-science.pdf

Q10. WS answer (3). My answer (1). I thought more milk will absorb more heat from the hot water at the same temperature.

For (2) and (4), the milk loses heat to the water. So not correct.

For (1) and (3), the initial temperatures of the milk and water are the same. As there is more milk in (1), the final temperature of the milk and water will be lower for (1). So the water loses more heat. Hence the milk gains more heat. (1) should be correct.

[For (1), as the milk gains heat from the water at the surface where they are in contact, the heat gained by the milk travels to the milk above the water level. Hence the milk for (1) is always at a lower temperature than (3). With a greater temperature difference, the heat gains by (1) will also be faster than (3) for the same given time. Hence (1) is correct.]


Q26. How could we determine which one has the greatest heat gain?
WS answer (2). Why not (1)?

(3) and (4) losed heat, hence definitely not correct.
With regard to (1) and (2), should temperature difference be the only factor to decide which gain the most heat.

Any comment on Q10 and please help on Q26.

I agree with answer of (1) for Q10. But the question should indicate that the volume of water is more than that of the milk.

Someone mentioned about heat loss from the exposed milk. It will have minimum contribution due to the extra exposed surface area not significantly more than the surface of the milk.

My intuitive answer for Q26 is (2). Another poorly constructed question. I think atutor already mentioned the issues.

It is not a simple case of temperature difference. 3 important data are missing: specific heat of fusion for water, specific heat capacity of water and the specific heat capacity of the metal.

If you do the math, the contribution from the melting of ice needs 3 times more energy than to bring the melted ice (0oC) to 25oC. If the specific heat capacity of metals and water I pulled out from the web is not wrong, and I assume that the metal is iron, and both metal and ice have the same mass, and I further assume that the volume of water is far in excess to the volume of ice and metal, then the heat gain by the ice is actually more than the heat loss by the metal. A really terribly wrong question.

PlasmaStorm:

ChiefKiasu:

[quote=\"Full.Cream\"]My kids were asking me similar qn, ie, how come water is in gaseous state in the air when it's not 100degC. How to answer this?

To answer this question, ask another question:
\"What is the boiling point of water in space, where there is zero atmospheric pressure?\"

There are two answers I can think of:
1) The diff between liquid and gaseous state is that the liquid is tightly packed together by intermolecular forces but less so if gas. So the gas has no definite volume. If you leave a bowl of water on the table, the water will start to evaporate as it has heat. Based on what my eldest brother and his secondary textbook taught me, heat is an illusion. it is actually kinetic energy. Heat causes the molecules in the substance, in this case water, to vibrate. When the water molecules vibrates, the vibration causes intermolecular forces causes the water molecules to vibrate and destroy the intermolecular forces within it, causing it to turn into a gas.

2)If you put water into a vaccum (which is where nothing is, not even air), it will turn into gas. The atmosphereic pressure helps the intermolecular forces to hold the molecules together keeping it in the liquid stage. BUT when there is no atmosphereic pressure, the intermolecular forces are too weak to hold the water molecules together. thus it boils.
(My 2nd reason was derived from what ChiefKiasu said. Thanks!)

Hope this helps!

From: PlasmaStorm :D[/quote]Intermolecular forces are a constant for a set of molecules and a specific value of average intermolcular distance. It will not change with pressure.