The two wires $A$ and $B$ of equal cross-section but of different materials are joined together. The ratio of Young's modulus of wire $A$ and wire $B$ is 20/11. When the joined wire is kept under certain tension the elongations in the wires $A$ and $B$ are equal. If the length of wire $A$ is 2.2 m , then the length of wire $B$ is

$\_\_\_\_$ m.

Eight mercury drops, each of radius $r$, coalesce to form a bigger drop. The surface energy released in this process is $\_\_\_\_$ - ( $S$ is the surface tension of mercury).

The Young's modulus of steel wire of radius $r$ and length $L$ is $Y$.

If the radius $r$ and length $L$ of the wire are doubled then the value of $Y$

Two wires as shown in the figure below, made of steel and have breaking stress of $12 \times 10^8 \mathrm{~N} / \mathrm{m}^2$. Area of cross-section of upper wire is $0.008 \mathrm{~cm}^2$ and of lower wire is $0.004 \mathrm{~cm}^2$. The maximum mass that can be added to pan without breaking any wire is $\_\_\_\_$ kg.