This study assessed the influence of the thermodynamic arrow of time on entropy for boiled cooling water (physical process), the universe and the air (natural process). This was done by determining the entropies of boiled water, the universe and air. Entropy can be thought of as a measure of microscopic disorder, implying that the Second Law of thermodynamics asserts that time is asymmetrical with respect to the amount of order in an isolated system. This was achieved by using 1.5 litres of pure water, a 2-liter electric kettle, a digital thermometer, a digital weighing scale and a stopwatch. The entropy values of boiled water as it was cooling, were in negatives, that of the universe was in negatives and positives and that of air (natural process) was positive. This showed that for any physical process, (boiled cooling water and the universe) thermodynamic arrow of time does not influence entropy in the positive direction while for a natural process (air), the thermodynamic arrow of time influences entropy in the positive direction. The world was both non-spontaneous and spontaneous, the boiling cooling water was a non-spontaneous process, and the air was a spontaneous process. The study has demonstrated that the thermodynamic arrow of time only affects the entropies of natural processes in a forward direction; however, the entropy of physical processes can be affected both forward and backward.