Biology Heat Loss Practical Write Up

Biology Coursework Practical – Heat Loss The aim of this practical is to find to what extent does the surface area to volume ratio of an object affect the rate of heat loss from the object Hypothesis: As the ratio of surface area to volume of an object decreases the rate of heat loss from the object will also decrease. Objects with the same surface area to volume ratios loose heat at the same rate so long as there are not other variables involved. Background Knowledge: The surface area to volume ratio of an object is determined by dividing the surface area by the volume and putting it into a ratio of one. e.g. A flask of volume 200cm3 and a surface area of 160cm2 will have a surface area to volume ratio of: 160 ---- : 1 = 1.25 : 1 200 Objects that are not the same size but have the same surface area to volume ratios loose heat at the same rate. So a flask, with a volume of 200cm3 with a surface area of 160cm2 and a surface area to volume ratio of 1.25:1, will loose heat at the same rate as a similar flask of volume 625 and a surface area of 500 which also has a surface area to volume ratio of 1.25:1. However, generally when you increase the size of an object the surface area to volume ratio decreases so in this example it is very likely that the two flasks in question are different shapes. In this experiment the two flasks which will be used will different surface area to volume ratios as follows: 100 cm3 flask: Volume = 100, Surface Area = 115. Surface Area to Volume Ratio = 115 ---- : 1 = 1.15 : 1 100 500 cm3 flask: Volume = 500, Surface area = 330. Surface Area to Volume Ratio = 330 ---- : 1 = 0.66 : 1 500 As it is seen the ratio is lower in the 500 cm3 flask. This means that the rate of heat loss should be less than the 100 cm3 flask. Heat is lost by three different processes: * Conduction * Convection * Radiation.. Conduction is the process by which heat is transferred from on solid to