A cantilever truss is loaded and supported as shown in the figure given below. Find the out value of P, which would produce an axial force of magnitude 3KN in member AC.
Sol.: Find out in the member AC, DC and DF
Let T_{1} = Force in member AC T_{2 } = Force in member DC
T_{3} = Force in member DF
Draw the section line, which cut member AC, DC, and DF.
Consider the right portion of truss, as Force P is in the right portion. Taking moment about D,
∑M_{D} = 0
- T_{1} X AB + P X (AC - AD) + P X (AE - AD) = 0
-3 X 2 + P X 1.5 + P X 4.5 = 0
P = 1KN .......ANS