Question

A plane cantilever truss is loaded as shown in the figure. If a positive sign denotes tension and a negative sign compression, the axial force in the member 1 is

• A. $-5.33P$
• B. $-1.67P$
• C. $+2P$
• D. $+3P$

Answer 1

The correct option is C $+2P$

Cut a section as shown in figure



$\sum M_A=R_1\times 12-P\times 4-P\times 8-P\times 12=0$

$\therefore R_1=2P$