A particle is kept on the surface of a uniform sphere of mass 1000 kg and radius 1 m. The work done per unit mass against the gravitational force between them is
[G = 6.67 $$\times$$ 10$$^{-11}$$ Nm$$^2$$ kg$$^{-2}$$]
The Young's modulus of a rubber string of length $$12 \mathrm{~cm}$$ and density $$1.5 ~\mathrm{kgm}^{-3}$$ is $$5 \times 10^8 ~\mathrm{Nm}^{-2}$$. When this string is suspended vertically, the increase in its length due to its own weight is (Take, $$g=10 \mathrm{~ms}^{-2}$$ )
The lower end of a capillary tube is dipped into water and it is observed that the water in capillary tube rises by 7.5 cm. Find the radius of the capillary tube used, if surface tension of water is 7.5 $$\times$$ 10$$^{-2}$$ Nm$$^{-1}$$. Angle of contact between water and glass is 0$$\Upsilon$$ and acceleration due to gravity is 10 ms$$^{-2}$$.