Factors That Influence Heat Loss

I have been asked to investigate the link between colour and heat loss. Does the silver or the black cup lose its heat faster? HYPOTHESIS I think that the silver cup will retain the heat for a longer period of time than the black cup, I think this because the black cup will absorb the heat, where as the silver cup will reflect the heat back into the cup causing the black cup to cool down faster than the silver cup.

BACKGROUND INFORMATION CONVECTION – the hot water in both cups will have convection current in them. The hot water will rise and sink as the water begins to cool.

This means the heat energy is being passed on to the metal cup over most of its inner surface. CONDUCTION – the metal cups will get hotter as a result of the heat energy inside the cup. The water will pass on this heat energy due to the fact that metal is a good conductor of heat.

The heat energy will be conducted throughout the metal cup to the outer surface where it will be transferred to the air around the cup as radiation. RADIATION – hot objects (i. e. the metal cup) emit mainly INFRARED radiation, and the hotter the object the more radiation it will emit.

What Affects The Rate Of Heat Loss Through Radiation

How much radiation the object emits will depend on the surface. The black cup had a dark matt surface and therefore will emit more radiation. This will mean that the black cup will lose more infrared radiation than the silver cup (which is a poor emitter of infra-red radiation) and as a result it will lose its heat quicker than the silver cup over the same amount of time.

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EQUIPMENT * Thermometer  Metal cups (silver and black) Timer METHOD We started of with two cups one black and the other silver. Then we set up the apertures like the diagram above.

We then got boiling water and poured it equally into each cup, then returned the lid. After the lid was replaced we recorded the temperature every 5 minutes. SAFETY To ensure ultimate safety during this test I have to take a few safety factors into account. The main thing that I have to take into consideration is the fact that I have to use boiling water to o this experiment, this is very dangerous if misused as it can seriously burn and scar for life. The other safety feature also includes the boiling water but for a different reason.

As we are using the water near to a computer we have to be careful not to allow the water to come in contact with it, because if it does it could break the computer or worst still it could spark and harm one of us. FAIR TEST I could make sure that the same volume of water was poured into each cup also make sure that the water poured into the cups at the same time was also at the same temperature RESULTS Time (Minutes) Temperature (oc) silver cup Temperature (oc) black cup.

End of lesson Total drop in temp25 33 My results show me that the black cup lost the heat faster than the silver cup did Experiment number 2 I have decided to repeat my experiment using a computer. This will make it more accurate because with the use of the computer it is 99. 9% accurate and the is no gap for human error. Results 2 Elapsed Time Temperature Temperature 7 ANALYSING As time increased the temperature decreased, the black cup decreased / lost heat faster than the silver cup.

As time went on the black cup was consistently absorbing heat from the hot water inside the black cup, where as the silver cup consistently reflected the heat back into the cup. This is because the black cup loses heat quicker than the silver because lighter surface do not conduct heat as well as darker surfaces. EVALUATING My original hypothesis was correct- I think that the silver cup will retain the heat for a longer period of time than the black cup, I think this because the black cup will absorb the heat, where as the silver cup will reflect the heat back into the cup causing the black cup to cool down faster than the silver cup.