The units of modulus of rigidity are

$A$ cube has side length $5$ cm and modulus of rigidity $10^5$ $N$/m$^2$. The displacement produced by a force of $10$ $N$ in the upper face of cube is . . . . . . mm.

Two wires $A$ and $B$ of same length and of same material have radii $r_1$ and $r_2$ respectively. Their one end is fixed with a rigid support and at the other end,an equal twisting couple is applied. Then,the ratio of the angle of twist at the end of $A$ to the angle of twist at the end of $B$ will be ..............

Two wires of the same length and same material have radii $r_1$ and $r_2$. Their one end is fixed,and when an equal torque is applied to the other end,what is the ratio of their angular displacement?

The upper end of a wire of radius $4 \, mm$ and length $100 \, cm$ is clamped and its other end is twisted through an angle of $60^o$. The angle of shear is .......... $^o$.

$A$ uniform wire of length $L$ and radius $r$ is twisted by an angle $\alpha$. If the modulus of rigidity of the wire is $\eta$,then the elastic potential energy stored in the wire is .........