Viscosity in everyday life-
1. Lubricating oils are graded according to their viscosity. A good quality or 'all-weather' lubricating is one whose viscosity and hence lubricating property does not change much with increase of temperature. Such oils are obtained by adding long chain coiling polymers to the oil. As temperature rises, the polymer particles tend to uncoil and thus increase the viscosity of oil thereby compensating for the decrease of viscosity of the oil with rise of temperature.
2. The condition of high blood pressure and thus strain on heart may also be explained on the property of viscosity. In arteriosclerosis (hardening of arteries), arterial walls contract resulting in decrease of diameter of capillaries. Narrow capillaries offer resistance to the flow of blood due to viscosity with the result greater force is needed to make blood flow through capillaries. This results in a condition of high blood pressure and strain on the heart.
3. The increased blood circulation required during fever is supplied by its temperature dependence propery (recall that rise of every degree centrigrade temperature decreases viscosity of blood by about 3%). Thus lowering of viscosity results in a more rapid flew of blood without any extra strain on the heart.
4. In case of asphyxia, concentration of CO in blood increases resulting in swelling of corpuscles which then increases viscosity of blood.
