The strain energy stored in a body of volume $V$ due to shear strain $\phi$ is (shear modulus is $\eta$ ).

The upper end of a wire $1\,m$ long and $4\,mm$ radius is clamped. The lower end is twisted by an angle of $30^\circ$. The angle of shear is ...... $^\circ$.

Two wires $A$ and $B$ of the same length and of the same material have the respective radii $r_1$ and $r_2$. Their one end is fixed to a rigid support,and at the other end,an equal twisting couple is applied. 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?

$A$ rectangular block of size $10\,cm \times 8\,cm \times 5\,cm$ is kept in three different positions $P, Q,$ and $R$ in turn as shown in the figure. In each case,the shaded area is rigidly fixed and a definite force $F$ is applied tangentially to the opposite face to deform the block. The displacement of the upper face will be

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 .......... $^o$.