After effects of elasticity are maximum for

Consider two wires of the same material having their ratio of radii to be $2:1$. If these two wires are stretched by an equal force,then the ratio of stress produced in them is

Consider a long steel bar under a tensile stress due to force $F$ acting at the edges along the length of the bar (as shown in figure). Consider a plane making an angle $\theta$ with the length. What are the tensile and shearing stresses on this plane?
$(a)$ For what angle is the tensile stress a maximum?
$(b)$ For what angle is the shearing stress a maximum?

Which of the following statements is correct?

The length of a metal wire is $l_1$ when the tension in it is $F_1$ and $l_2$ when the tension is $F_2$. Then,the original length of the wire is

One end of a uniform wire of length $L$ and weight $W$ is attached rigidly to a point in the roof,and a weight $W_1$ is suspended from its lower end. If $S$ is the area of cross-section of the wire,the stress in the wire at a height $3L/4$ from its lower end is