Strain is a unitless quantity.

A mild steel wire of length $2 L$ and cross-sectional area $A$ is stretched, well with in the elastic limit, horizontally between two pillars as shown in figure. A mass $m$ is suspended from the mid-point of the wire. Strain in the wire is

A block of mass $\mathrm{4 }\text{kg}$ is suspended from the ceiling with steel wire of radius $\mathrm{2 }\text{mm}$ and negligible mass. Find stress in the wire (Given$g={\pi }^2$)

A rod is made of uniform material and has non-uniform cross section. It is fixed at both the ends as shown and heated at mid-section. Which of the following statements are not correct ?