$(1)$ \[ \begin{align} \sigma=\frac{P}{A} &=\frac{1500\times9.8}{(30\times10^{-3})^2}\\ &=1.63\times10^1\ \rm{MPa} \end{align} \] $(2)$ \[ \sigma=E\epsilonより \] \[ \begin{align} \epsilon=\frac{\sigma}{E}&=\frac{16.33}{206\times10^9}\\ &=7.93\times10^{-5} \end{align} \] $(3)$ \[ \nu=-\frac{\epsilon'}{\epsilon}より \] \[ \begin{align} \epsilon_y=-\nu\epsilon_x=&-0.3\times7.929\times10^{-5}\\ &=-2.38\times10^{-5} \end{align} \] $(4)$ \[ \epsilon_V\simeq\epsilon_x+\epsilon_y+\epsilon_z \] $(5)$ \[ \begin{align} \Delta V&=\Delta\times\epsilon_V\\ &=\left(\left(30\times10^{-3}\right)^2\times2\right)\times(1-2\nu)\times7.929\times10^{-5}\\ &=5.71\times10^{-8}\ \rm{m^3} \end{align} \]