Question

A sagging floor is jacked up and a steel girder 3.03 m long whose cross-sectional area is 6.0 in square is put in place underneath. when a jack is removed, a sensitive gauge that the girder has been compressed by 0.020 cm. Find the load the girder is supporting. use metric system units.  

Answer 1

Answer

Young's modulus of steel at room temperature is typically between 190GPa.

$Area=6 in^2=9300m^2$

Compressed length

l=0.0002m

Initial Length L=3.03m

the load the girder is supporting is given by

$W=\frac{YAl}{L}\\=\frac{19\times10^{10}\times9300\times0.0002}{3.03}\\=1.67\times10^{11}Kg$