A small spherical body of radius r and density $$\rho $$ moves with the terminal velocity v in a fluid of coefficient of viscosity $$\eta $$ and density $$\sigma$$. What will be the net force on the body?

The stress along the length of a rod (with rectangular cross-section) is 1% of the Young's modulus of its material. What is the approximate percentage of change of its volume? (Poisson's ratio of the material of the rod is 0.3).

What will be the approximate terminal velocity of a rain drop of diameter $${1.8 \times {{10}^{ - 3}}}$$ m, when density of rain water $$ \approx $$ $${1.8 \times {{10}^{ - 5}}}$$ N-sm^$$-$$2 (Neglect buoyancy of air)

A uniform capillary tube of length l and inner radius r with its upper end sealed is submerged vertically into water. The outside pressure is p₀ and surface tension of water is $$\gamma$$. When a length x of the capillary is submerged into water, it is found that water levels inside and outside the capillary coincide. The value of x is