Point out the right statements about the validity of Kirchhoff’s junction rule,
Four particles each of the mass m are placed at the corners of a square of side length $$l$$. The radius of gyration of the system about an axis perpendicular to the square and passing through its centre is
A steel wire of length 4.7 m and cross-sectional area $$3.0\times10^{-5}$$ m$$^2$$ stretches by the same amount as a copper wire of length 3.5 m and cross-sectional area of $$4.0\times10^{-5}~\mathrm{m^2}$$ under a given load. What is the ratio of Young's modulus of steel to that of copper?
The masses of 200 g and 300 g are attached to the 20 cm and 70 cm marks of a light meter rod, respectively. The moment of inertia of the system about an axis passing through 50 cm mark is