A steel rod shaped as a cylinder and having negligible weight has a diameter of $1.5\text{ cm}$ and a length of $5.2\text{ cm}$. Its upper end is rigidly fixed. At the other end, the rod is fixed to a machine that exerts a steady force of $363\text{ N}$ on it. As a result, the rod stretches until its length becomes $7.4\text{ cm}$ and, at the position shown, its smallest diameter is $0.60\text{ cm}$. What is the maximum stress in the steel rod when its length is $7.4\text{ cm}$?
- A$2.1\times10^{6}\,\text{Pa}$
- B$3.2\times10^{6}\,\text{Pa}$
- C$5.7\times10^{6}\,\text{Pa}$
- D$1.3\times10^{7}\,\text{Pa}$