PSLE 2012 - Science

[James Ang]

BeContented:

James Ang:

[quote=\"kiasu学生\"]

ill try

Q: Some buildings use a cooling mist system 2 lower the temperature of the surroinding air. the mist comes out in the form of small water droplets.

Q: How does the cooling mist system help 2 lower the temp of the surrounding air? (2m)

some fans were added 2 the coolinf mist systeem.

Q: how do the fans help in the cooling mist system? (1m)

that should be this pprs killer Q

Evaporation of mist takes away heat and causes cooling as heat is required to change the mist from liquid state to water vapour which is gaseous state. By creating mist instead of using only water, the surface area of the water is increased and the greater the exposed surface area, the greater the rate of evaporation.

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.

DS says 'Wah. This answer way better than mine'.
Thanks to you too.[/quote]This type of mist producing fans can be seen at some outdoor coffee shops and cafes especially in hot weather Singapore.

[Big fish]

Kiasukiasuofall:

Diedie...I wrote the surrounding air loses heat to the water droplets which lower the temperature...will I get partial marks?

My ds wrote this too

[BeContented]

Big fish:

Kiasukiasuofall:

Diedie...I wrote the surrounding air loses heat to the water droplets which lower the temperature...will I get partial marks?

My ds wrote this too

DS too.

[concerned_of_PSLE 10]

So hard i almost wanted to commit suicide inside

Still got hcl tmrw
Wishing to be a normal chinese pupil
:imdrowning: :?:

[concerned_of_PSLE 10]

So hard i almost wanted to commit suicide inside

Still got hcl tmrw
Wishing to be a normal chinese pupil
:imdrowning: :?:

[concerned_of_PSLE 10]

So hard i almost wanted to commit suicide inside

Still got hcl tmrw
Wishing to be a normal chinese pupil
:imdrowning: :?:

[concerned_of_PSLE 10]

So hard i almost wanted to commit suicide inside

Still got hcl tmrw
Wishing to be a normal chinese pupil
:imdrowning: :?:

[Sun_2010]

concerned_of_PSLE 10:

So hard i almost wanted to commit suicide inside

Still got hcl tmrw
Wishing to be a normal chinese pupil
:imdrowning: :?:

:hugs: Things are never as bad as they seem.

Chin up and attack your HMT.

[vaidyanathan padmini]

kiasu学生:

Alex_:

Booklet A is kinda easy, booklet B is hard.. -_-\"


What about the control set-up question?

not really sure abt that have my doubts...

I put option 4..... the closed beaker with water and grn bean seeds on damp cloth, should not remove co2 as it changes the experiments aim and outcome completely, if remove oxy. then its not a control, so I put water but I mb wrongg.

My dd's answer is also 4 :xedfingers:

[atutor2001]

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.