Solució: \begin{align} p &= \cssId{Step1}{ \frac {P_h}{q}}\\[3px] &\cssId{Step2}{\frac {847,9}{0,2985}= 2840 MPa } \\[3px] &\cssId{Step3}{R_m= \frac{U^2}{P_2}-R_e = 127,9 } \\[3px] \end{align}