Question

A simple plane truss is shown in figure. Two $1000N$ loads are acting on pins $C$ and $E$ as shown. The force in member $CD$ is

• A. $1000N$
• B. zero
• C. $1000\sqrt{2}N$
• D. $-1000/\sqrt{2}$

Answer 1

The correct option is B zero

Taking moment about A and F, we will get

$R_A=R_F=1000N$

Cut section $XX$ as shown in figure.

Let $F_{BD}$ be the force in member $BD$, $F_{CD}$ be the force in member $CD$ and $F_{CE}$ be the force in member $CE$.

$\Sigma F_y=0$

$-F_{CD}\sin 45-1000+1000=0$

$F_{CD}=0$