A small test

How much irrigation thermos flask, its insulation works best?

Thoughts: For this problem we can first do an experiment.

Experimental Equipment: thermos flask (four identical),water,thermometer

1、First understand thermos household may be used in the following situations:

(1) The water filled;

(2) When water is about to be filled,leaving a small amount of air;

(3) filling only half a bottle of water;

(4) Only a small bottle of water irrigation.

2、The four thermos by filling more than four cases on the same temperature water.

3、The four thermos place the same time.

4、Measuring the water temperature,the level comparison.

Experimental phenomena:find the second case (when the water is about to be filled,leaving a small amount of air) insulation works best.

Experimental results and the reasons:When the bottle with no irrigation and leave a small amount of air (the distance between the stopper and the water surface is generally 2 to 3 cm),thermos insulation effect for the best. Because the heat transfer efficiency of the water is four times that of air,that air is a poor thermal conductivity in the water,so that the heat of hot water bottle will less easily through the air layer above the water in the mass to pass stopper to go outside,so the insulation effect is better.Conversely,if the thermos filled with water,the water will be the cork wet,then the heat will water as media and quickly spread to the bottle,so the insulation effect on hearing.