One end of a wire of $8 \,mm$ radius and $100 \,cm$ length is fixed and the other end is twisted through an angle of $45^{\circ}$. The angle of shear is (in $^{\circ}$)

$A$ wire can be broken by applying a load of $200\, N$. The force required to break another wire of the same length and same material,but double in diameter,is .......... $N$.

$A$ spring is stretched by applying a load to its free end. The strain produced in the spring is

What is the tangential stress on the cross-section $PQRS$?

Mark the wrong statement.

$A$ rod of length $1.05 \; m$ having negligible mass is supported at its ends by two wires of steel (wire $A$) and aluminium (wire $B$) of equal lengths as shown in Figure. The cross-sectional areas of wires $A$ and $B$ are $1.0 \; mm^{2}$ and $2.0 \; mm^{2}$ respectively. At what point along the rod should a mass $m$ be suspended in order to produce $(a)$ equal stresses and $(b)$ equal strains in both steel and aluminium wires?