1. The problem statement, all variables and given/known data consider a horizontal cylindrical tube of cross sectional area A fitted with two frictionless pistons. The piston are connected to each other by an inextensible wire. Initially, the temperature of the gas is To and its pressure is Po which equals the atmospheric pressure. Find the tension in the wire if the temperature is raised to 3To. 2. Relevant equations (P1V1)/T1=(P2V2)/T2 3. The attempt at a solution Using the above equation; as volume is constant, new pressure P'=3Po. So, force applied on one piston=3PoA Equating with the force from atmospheric pressure outside the tube, 3PoA=PoA+T So T=2PoA ; which is the required answer. My question is, isn't this the force on one cross section of the wire? So why isn't this answer multiplied by two? Thank you for your time!