Introduction:
Kinematic viscosity is a measure of a fluid's resistance to flow under the influence of gravity. It is defined as the ratio of dynamic viscosity to density. In simpler terms, it indicates how easily a fluid flows. The kinematic viscosity of a fluid depends on its molecular structure and temperature.

Kinematic viscosity of water:
Water is a common fluid with a relatively low kinematic viscosity. At 20°C, the kinematic viscosity of water is about 1.003 × 10^-6 m^2/s. This means that water flows easily compared to other fluids with higher kinematic viscosities.

Kinematic viscosity of mercury:
Mercury, on the other hand, has a much higher kinematic viscosity compared to water. At 20°C, the kinematic viscosity of mercury is about 1.53 × 10^-7 m^2/s. This makes mercury less flowable compared to water. Due to its higher kinematic viscosity, mercury tends to flow more slowly and is more resistant to flow.

Comparison between water and mercury:
When comparing water to mercury, it is evident that water has a higher kinematic viscosity than mercury. This means that water flows more easily compared to mercury. The lower kinematic viscosity of water is due to its molecular structure, which allows for freer movement of water molecules compared to the larger and heavier mercury molecules.

Temperature effect:
It is important to note that the kinematic viscosity of both water and mercury is temperature-dependent. As temperature increases, the kinematic viscosity of both fluids decreases. This is because the increase in temperature causes the fluid molecules to move more rapidly, reducing their internal friction and hence decreasing their resistance to flow.

Conclusion:
In conclusion, the kinematic viscosity of water is higher than that of mercury. Water flows more easily due to its lower kinematic viscosity. However, it is important to consider that the kinematic viscosity of both fluids is temperature-dependent, and as temperature increases, their kinematic viscosity decreases.