Question

The force in member BC of the truss shown in figure below is

• A. $500N\text{(tensile)}$
• B. $800N\text{(compressive)}$
  
• C. $800N\text{(tensile)}$
• D. $500N\text{(compressive)}$

Answer 1

The correct option is C $800N\text{(tensile)}$


$\sum M_A=0$

$1200\times 8+400\times 3-R_3\times 12=0$

$R_3=900N$

$\sum F_y=0$

$R_2+R_3=1200N$

$R_2=300N$

$\sum F_x=0$

$R_1+400=0$

$R_1=-400$

By using method of section and cutting section at a-a



Taking moment about G

$300\times 4+400\times 3-F_{BC}\times 3=0$

$F_{BC}=800N$ (Tensile)