Question

A vertical steel post of diameter 25 cm and length 2.5 m supports a weight of 8000 kg. Find the change in length produced Y = 2x 10¹¹ Pa.

• A. 2.1 cm
• B. 0.21 cm
• C. 0.21 mm
• D. 0.021 mm

Answer 1

Answer: (C)

0.21 mm

Answer 2

∆l = $\frac{Fl}{AY} = \frac{4 \times 8000 \times 10 \times 2.5}{\pi(.25)^{2} \times 2 \times 10^{11}} = \frac{4 \times 16 \times 10^{- 5}}{\pi} = 0.21mm.$