$($adapted from Hibbeler ${10}^{th}$ ed$.$ prob. $12-128)$ Each of the two members is made from $6061-$T$6$ aluminum and has a square cross section $1in.{?}^{**}1in.$ They are pin connected at their ends and a jack is placed between them and opened until the force it exerts on each member is $50$ lb $.$ Determine the greatest force $P$ that can be applied to the center of the top member without causing either of the two members to yield. For the analysis neglect the axial force in each member. Assume the jack is rigid.

Answer: $243$ lb