[jack1234]

I am working on the other question.

"Group A thought that wind generated by an electric fan would keep an ice cube cool as it made our body cool off. They said we could feel that fan wind decreased our body temperature. So they thought that fan wind would prevent an ice cube from getting warmer.

However, Group B had a different idea.  They thought tha tthe temperature of room air was higher than an ice cube so they believed that fan would effectively deliver room air to an ice cube, which resulted in an ice cube getting warmer quickly.

Both groups set an ice cube in front of an electric fan and turned the fan on. At the same time, they placed the same size of another ice cube on a plastic dish to compare. Group A predicted that the ice cube exposed to fan wind would melt more slowly than the one on the plastic dish. However, Group B's prediction was opposite to Group A. Group B predicted that the ice cube exposed to fan would melt faster than the one on the plastic dish.

10 Minutes later, students observed that the ice cube exposed to fan wind almost melted while only half of the one on the plastic dish melted. So they observed that the ice cube exposed to fan wind melted more quickly that th eone on the plastic dish.

This are the questions and answers that i had

1) Based upon the abbove story what do you think the conclusion of experiment was.

" some of the conclusion that i can think of is that fan creates the air warmer which melts the ice faster."

2) What do you think th epurpose of the experiment was?

" The purpose of the experiment was to teach the students regarding the heat transfer."

3) What do you think kids from group a and b learn from experiment
"Kids from Group A learned that, not always what we think is usually the truth until you try it."

 

[enahs]

Why does a fan cool a person off? Perspiration. You always have a small amount (or large after a lot of activity) of sweat being excreted from your skin. Air flow increases the rate of evaporation (usually, not always, but under virtually any normal or typical conditions this is true).

You can read more about evaporation and factors effecting it at Wikipedia.


*edit* To clarify why evaporation of sweat cools you off. Water is a wonderful substance in so many ways, and one of the weighs is how much energy in the form of heat it can "hold". By brining the water in contact with the skin, some of the energy in the form of heat goes into the water, and when the water evaporates it takes that energy (heat away with it).

[lemonoman]

To put it another way:

The air in the room is warmer than the ice cube.  Heat always goes from hotter to colder.

Warm air will cool down when it encounters something cold (like an ice cube)

A cold ice cube will warm up when it encounters something warmer (like room-temperature air)

The reason the ice cube melted faster with the fan is because it was exposed to MORE warm air than the one that just sat there.  As the ice cube melts, it cools the air around it.  If the ice cube is just sitting there, then the air around it is now cold and the ice cube can't really get much warmer.  But if a fan is pushing the air away, then a new supply of warm air is always there to warm up the ice cube.

1) Based upon the abbove story what do you think the conclusion of experiment was.

" some of the conclusion that i can think of is that fan creates the air warmer which melts the ice faster."

It doesn't make the air warmer...it just exposes the ice cube to more air.

2) What do you think th epurpose of the experiment was?

" The purpose of the experiment was to teach the students regarding the heat transfer."

Pretty much.

3) What do you think kids from group a and b learn from experiment
"Kids from Group A learned that, not always what we think is usually the truth until you try it."

That's true, they did learn that.  But this isn't the answer they are looking for.
You said in your answer to #2 that the purpose of the experiment was to teach the students about heat transfer.  So...what DID they learn about heat transfer?

[IITian]

Case I: Natural or Free Convection

Case II (using the fan): classic example of Forced or assisted convection