Hi Hi, this is my first post here.

Which of the following freeze into ice first when they are put in refrigerator, a cup of cold water or a cup of hot water?

cold

Would you give me some explanation or some calculation?

Should have seen that one coming. Sry.

The cup with the cold water will freeze the fastest as the cup with the hot or warm water has more heat in it. Therefore the excess heat must 1st be lost before you can go on to the freezing phase.

 

Calculation? I don't think that one is necessary here.

"More heat in it"?

Hot water may freeze faster!

 

here: http://math.ucr.edu/home/baez/physics/General/hot_water.html

But ad, the rate of losing heat for hot water is much faster than cold water.

Let's say, 100 deg Cel for hot water and 10 degree CEl for cold water, then you can see that rate.

So I think calculation may be needed as the rates are playing "chase and chase"

In some conditions the hot water will freeze first, in some conditions the cold.

 

There are many reasons why, for example.

 

Hot water will evaporate much faster than cold, this means that there is less water in the cup to freeze, which speeds up the freezing. Secondly, evaporation takes up energy, energy which comes from the hot water. As the energy is being lost due to evaporation, the water left behind is cooling.

 

hope that helps...

Thanks YTTYTYTYTYTY

Hot water may freeze faster!

 

here: http://math.ucr.edu/home/baez/physics/General/hot_water.html

 

Err, I stand corrected.

Thanks for the link YT.

 

I guess I should stay out of the Physics sections

Don't do that.

I always do bad jobs in my quizs but I never give up

Do you guys always watch the document in your monitor ?

I always print them out and watch when I turn off the computer.

Does anyone know that whether printing black words would use coloured ink ?

Depends on the printer.

 

If it only has a colour cartridge, it will make black by combining all 3 colours.

Do you guys always watch the document in your monitor ?

I always print them out and watch when I turn off the computer.

 

Good point in the above post(11).

As for this, I despise reading long papers/articles on the screen, so I print them out.

Especially for me, I use CRT Monitor, HaRSH.

That makes me never go through paper on the screen.

I want to buy a LCD mon without myself.

What brand and which do you suggest for me ?

Not higher than HKD$2500,ok?

ViewSonic monitors are superb.

 

http://www.tigerdirect.com/applications/Category/category_tlc.asp?CatId=12&SRCCODE=WEBGOO0061A&CMP=KNC-GOOGL