Radiation.
Heat could be lost through radiation. Heat travels as waves in space, this is known as radiation. Hotter objects radiate more heat than cooler ones and black surfaces absorb and give out heat well. Because of this we will not be using a black cup as it clearly would have a large heat loss due to radiation. A shiny surface would be ideal to reflect radiation. Because of this we will also test the cups with a coating of tin foil. This will effect the results. A dark colour cup will absorb heat so I predict the brown cup will not be efficient.
Conduction
Conduction is the transfer of heat or electricity through a substance resulting from a difference in temperature in different parts of the substance. Since heat is energy which is associated with the motions of the particles making up the substance, it is transferred by the motions, moving from regions of higher temperature, where the particles are more energetic, to regions of lower temperature. The rate of heat flow between two regions is relative to the temperature difference between them and the heat conductivity of the substance. Insulation can be used to stop conduction. Because of this I predict the polythene cup will be the superior cup.
I will be investigating the factor of radiation by testing the overall cup that sustains a higher temperature for longer once without a tin foil covering and once with. I will also be investigating convection by performing the cup with and without a lid. I will be checking the temperature of the water every minute for fifteen minutes. The cups I will be using are; Blue plastic cup, White plastic cup, Polythene cup, Vitamax cardboard cup, and a brown plastic cup. I predict the polythene with silver foil will keep the liquid hotter than the others. This is because I believe a lot of heat will be lost through radiation so the foil will stop this and the polythene cup has the best insulation. To make this experiment a fair test I shall be using 100ml of water each time. The equipment I will need is; the cups themselves, kettle, thermometer, tin foil.
A diagram of the experiment I will be performing:
My initial Results
These results are inaccurate as the starting temperatures are dissimilar. Because of this I produced a different table with all results being added-to so that the starting temperature is 90 for each cup.
My adjusted results
As these results show, the polythene cup covered in silver foil managed to keep the liquid hottest for the longest time. This proves my prediction. The white plastic cup came second in terms of keeping the liquid hottest.
A scatter diagram of the white plastic cup.
A scatter diagram of the polythene cup with silver foil
The circled points of the above graphs are anomalous results, these results do not fit in with the trend of results. This could be due to a misread temperature or perhaps the temperature was recorded not exactly on the minute.
The observations I have made are not as accurate as they could be. I could have made it a fairer test by rechecking that all results were recorded exactly on the minute. Also I could have used the digital data collectors instead of an ordinary thermometer. As further work I would like to try the polythene cup with silver foil and a lid. I feel this would vastly decrease heat loss.
