A stone of mass $$2 \mathrm{~kg}$$ is hung from the ceiling of the room using two strings. If the strings make an angle $$60^{\circ}$$ and $$30^{\circ}$$ respectively with the horizontal surface of the roof then the tension on the longer string is : $$g=10 \mathrm{~ms}^{-2}$$
A parallel plate capacitor is filled by a dielectric whose relative permittivity varies with the applied voltage (U) as $$\epsilon=2 U$$. A similar capacitor with no dielectric is charged to $$U_0=78 \mathrm{~V}$$. It is then connected to the uncharged capacitor with the dielectric. Find the final voltage on the capacitors.
If the ratio of lengths, radii and Young's Moduli of steel and brass wires in the figure are $$\mathrm{a}, \mathrm{b}$$ and $$\mathrm{c}$$ respectively, then the corresponding ratio of increase in their lengths would be