PSLE 2012 - Science

[fantasy1]

may I know what is yr answer?

[atutor2001]

creamyhorror:

atutor2001:

[quote=\"James Ang\"]
The use of fans creates wind which is moving air and the presence of wind increases the rate of evaporation and produces a greater cooling effect.

Fan is used to disperse the mist to reach different parts of the room so that the room will cool down at a faster rate. It is also to prevent the tiny water droplets from combining into large droplets (precipitation like rain cloud) that would fall to the floor and wet the room.

I think all 3 points are correct. Higher air movement inherently results in an increased evaporation rate.
[/quote]In normal cases of evaporation, the water is a \"huge\" body that does not move. So wind helps to remove the \"hotter\" and more humid air surrounding this water body, replacing it with cooler air and less humid air. As a result, the rate of evaporation will increase.

For this question, the mist are tiny water droplets that follows the wind. So the water droplets will move with the wind to different parts of the room, gaining heat from that part of the room where it has reached and evaporates.

[fantasy1]

What is the answer for the water setup qn :?

[777]

Anybody know the answer for the ballon question in booklet A? (the question is something like why the ballon become smaller in the refrigerator?)


My answer is 2

[fantasy1]

MY DD option is (4) . May I know what is option (2)

[777]

Can’t remember. Only know that i put option 2. Wat is option 4 ?

[Active kid]

777:

Can't remember. Only know that i put option 2. Wat is option 4 ?

I also put (4) --The air in the balloon had lost heat to the material of the balloon.

[Active kid]

I like to check about the question about a beaker of hot water at a high temp. and what is the best way to cool it down the fastest.What is the answer?


Thanks.

[thesjarox]

Active kid:

I like to check about the question about a beaker of hot water at a high temp. and what is the best way to cool it down the fastest.What is the answer?


Thanks.

I put the metal spoon and the wet cloth.

[Active kid]

thesjarox:

Active kid:

I like to check about the question about a beaker of hot water at a high temp. and what is the best way to cool it down the fastest.What is the answer?


Thanks.

I put the metal spoon and the wet cloth.

Same here
:thankyou: