Wednesday, September 24, 2008

mythbuster experiment

Can warm water freeze faster than cold water?

Surprisingly, yes it can. Warm water can freeze faster than cold water, provided the proper conditions are in place. When it does happen, it is known as the Mpemba Effect.


To demonstrate it yourself you will need:

  • two identical containers of the same size and shape
  • access to cold water
  • A kettle
  • A freezer large enough to hold both of your containers

1. Fill each container with the same amount of water, but make sure that the initial temperature of the water in each container is slightly different - starting temperatures of 70 degrees centigrade and 30 degrees centigrade, respectively, work well. You could use water from the cold tap that has been allowed to stand at room temperature for 5 minutes and water that has been boiled in the kettle and allowed to cool for 3-5 minutes.

2. Put both containers in the freezer.

3. As the water in the containers cools, you will find that the container with the warmer water (70 degrees) will freeze faster than the container with the cooler water (at 30 degrees).

This defies immediate logic and even scientists are not in agreement about exactly how it happens. The main factors that are broadly agreed on are that freezing the hotter water affects its scientific properties. Some of it evaporates so there is less to freeze, the way heat moves through it changes, the gases in it change, it affects its surroundings in the freezer and also experiences a phenomenon called supercooling, which means that it can freeze at a slightly higher temperature than colder water.

For such an everyday substance, water is surprisingly complex and it doesn't always behave as expected. But at least we can prove one myth about it is true!

3 comments:

Azzwaa said...

nampak sgt ko sgt la boriiiiing!
hahahaa...
nie nk lwn david copperfield lak nie



p/s:
bln2 pose nie org xletak ar gmbr2 sensored nie!(gmbr air terjun!)

ijamdbest said...

hehe..jgn jeles le ajue..hehe..klo ngok gmbar 2 cb ko byg btapa sejuk nye air 2..haha..nyaman nye..hehe..mmg ngah boring yg teramat ni..hehe..mggu dpn blk lgkw..

budak cari hari said...

anda ditag!
refer blog saya untuk t&c
(: