Courseworks

What factors affect 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?HYPOTHESISI think that the black cup will lose heat faster then the silver cup.BACKGROUND INFORMATIONCONVECTIONThe 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.CONDUCTIONThe 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.RADIATIONHot objects (i.e. the metal cup) emit mainly Infrared radiation, and the hotter the object the more radiation it will emit. 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.EQUIPMENT* Thermometer* Metal cups (silver and black)* Timer* Hot waterMETHOD* The equipment was set up as in the diagram.* We put boiling water into each cup and put the lid back on.* We then recorded the temperature every 5 minutes.SAFETY* Be careful of the boiling water.* Wear goggles for protection.FAIRTESTTo make it a fair test we timed the same amount of time and hot water for both cups and we started the experiments at the same time.RESULTSTime (Minutes)Temperature (oc) silver cupTemperature (oc) black cup09190585.583108177157871207467257163.5306860356657406354Total drop in temp2836My results show me that the black cup lost heat faster then the silver cup as the temperature decreases the time increases.Experiment number 2I have decided to repeat my experiment using a computer. This will make it more accurate because we can keep the results up for a long time and the computers result is more accurate.Results 2Elapsed TimeTemperatureTemperature5438.540.2Minutes�C�C5538.139.8091.584.65637.739.4189.4855737.339287.685.65836.938.7385.884.25936.538.248482.86036.237.8582816135.837.4680.279.56235.537.1778.778.36335.236.7877.276.96434.936.4975.775.66534.5361074.374.36634.235.81172.873.16733.935.51271.371.76833.635.21369.870.46933.334.91468.769.3703334.61567.568.37132.734.41666.367.17232.434.11765.266.17332.133.8186465.17431.933.51962.964.27531.633.22061.863.17631.5332160.862.17731.232.72259.761.2783132.52358.860.27930.732.22457.859.48030.532255758.58130.231.82656.157.7823031.62755.2578329.831.42854.456.28429.531.22953.655.48529.330.93052.854.78629.130.73151.9548728.930.53251.153.28828.630.33350.452.58928.430.13449.651.89028.229.93548.951912829.73648.250.49227.929.53747.649.79327.729.3384749.19427.429.13946.348.59527.328.94045.747.89627.128.64145.147.39726.928.44244.546.79826.728.34343.946.19926.628.14443.345.610026.427.94542.74510126.227.74642.244.51022627.64741.74410325.927.44841.243.510425.727.34940.74310525.627.15040.242.310625.4275139.741.610725.326.85239.34110825.226.75338.940.610925.126.511024.926.416620.621.611124.826.316720.521.611224.726.116820.521.511324.525.916920.421.411424.425.817020.421.411524.325.717120.421.311624.225.517220.321.311724.125.517320.321.21182425.317420.221.111923.925.217520.22112023.725.117620.22112123.62517720.12112223.524.917820.12112323.424.817920.120.912423.324.71802020.912523.224.71812020.912623.124.618219.920.71272324.518319.920.71282324.318419.820.712922.924.318519.820.613022.824.218619.820.613122.724.118719.820.513222.62418819.620.513322.623.918919.620.513422.523.819019.620.413522.423.719119.520.413622.323.619219.520.313722.323.519319.520.313822.223.419419.520.313922.123.319519.420.21402223.319619.420.21412223.219719.420.214221.923.119819.320.114321.82319919.320.114421.822.920019.320.114521.822.9Total drop72.264.514621.722.814721.622.714821.622.614921.522.515021.422.515121.422.415221.322.315321.322.315421.222.215521.222.21562122.1157212215821221592121.916020.921.916120.921.816220.821.816320.721.816420.721.716520.621.7ANALYSINGAs the time increased the temperatures of both cups decreases. The black cup lost heat faster then the silver cup. The silver cup lost heat slower then the black cup because its light reflects heat back into the cup keeping the water warm. Both cups dropped down a lot in temperature at the beginning then they slowed down near the end.EVALUATINGMy original hypothesis was correct and the black cup lost heat faster then the silver cup. In conclusion the black cup lost heat faster then the silver cup.There is an anomaly, which is a strange result in the graph, which is a point in the graph where the Silver cup lost heat faster, then the black cup. This was at 85 degrees Celsius. There are some improvements that I could do to make the practical more reliable. For example I could do the same experiment a few times to see if the results are about the same.

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