<>= typ <- if(match_exams_call() %in% c("exams2pdf", "exams2nops")) ".pdf" else ".svg" sup <- c("image68_1.eps") sup <- gsub(".eps", typ, sup, fixed = TRUE) include_supplement(sup, recursive = TRUE) @ \begin{question} A very long cylinder with the cross-sectional area of an equilateral triangle of side length $a$ and specific weight $\gamma_r$ is submerged. \begin{center} \includegraphics[scale=0.8]{image68_1\Sexpr{typ}} \end{center} The water pressure at the bottom is $u=\gamma_w \cdot \frac{\sqrt{3}}{2} a$. The buoyancy force per linear meter of the cylinder is \begin{answerlist} \item $A_w = u \cdot a = \gamma_w \cdot \displaystyle \frac{a^2\sqrt{3}}{2}$ \item $A_w = \gamma_w \cdot \displaystyle \frac{a^2\sqrt{3}}{4}$ \item $A_w = (\gamma_r-\gamma_w) \cdot \displaystyle \frac{a^2\sqrt{3}}{4}$ \item $A_w = \gamma_w \cdot a^2$ \item $A_w = \gamma_w \cdot \displaystyle a^2 \sqrt{\frac{3}{16}}$ \item $A_w = \gamma_w \cdot \frac{\sqrt{3}}{2} a$ \item $A_w = \gamma_w \cdot a \cdot \frac{1}{2} \left(\frac{\sqrt{3}}{2} a \right)$ \end{answerlist} \end{question} \exname{Exercise 68 (groundwater)} \extype{mchoice} \exsolution{0100101} \exshuffle{4} \exextra[difficulty,numeric]{1} \exextra[category,character]{groundwater}