NCERT Solutions for Chapter: Mechanical Properties of Fluids, Exercise 4: SA

The sap in trees, which consists mainly of water in summer, rises in a system of capillaries of radius $r=2.5\times {10}^{-5}\text{m}$. The surface tension of sap is $T=7.28\times {10}^{-2} \frac{\mathrm{N}}{\mathrm{m}}$ and the angle of contact is $0°$. Does surface tension alone account for the supply of water to the top of all trees?
 

The free surface of oil in a tanker, at rest, is horizontal. If the tanker starts accelerating the free surface will be titled by an angle $\theta$. If the acceleration is $a\frac{m}{s^2}$, what will be the slope of the free surface?.
 

Two mercury droplets of radii $0.1\text{ cm}$. and $0.2 \text{cm}$ coalesces into one single drop. What amount of energy is released? The surface tension of mercury $T=435.5 \times {10}^{-3} \frac{\mathrm{N}}{\mathrm{m}}$.
 

If a drop of liquid breaks into smaller droplets, it results in lowering of temperature of the droplets. Let a drop of radius $R$, break into $N$ small droplets each of radius $r$. Estimate the drop in temperature.
 

The surface tension and vapour pressure of water at $20°\text{C}$ is $7.28\times {10}^{-2} {\text{Nm}}^{-1}$ and $2.33\times {10}^3 \text{Pa}$, respectively. What is the radius of the smallest spherical water droplet which can be formed without evaporating at $20° \text{C}$?