Question 26.3.40: A thin cylinder of radius r and thickness t when subjected t...

(c)

EXPLANATION

Radial displacement = u
Initial radius = r
Final radius = r + u

Tangential strain = Circumferential strain = \frac{\text { Final circumference }-\text { Initial }}{\text { Initial circumference }} \\ \space \\ =\frac{2 \pi(r+u)-2 \pi r}{2 \pi r}=\frac{2 \pi u}{2 \pi r}=\pmb{\frac{ u }{ r } .}