Answer
$F=8200N$
Work Step by Step
$P=\frac{nRT}{V}$
$\frac{P_i}{P_f}=\frac{\frac{nRT}{V}}{\frac{nRT}{V}}=\frac{T_i}{T_f}=\frac{15^oC+273K}{165^oC+273K}=0.658$
$P_f=\frac{1 atm}{0.658}=1.52 atm$
$A=(^3\sqrt{6.15\times10^{-2}m^3})^2=0.156m^2$
$F_i=AP=(1.52 atm\frac{101325\frac{N}{m^2}}{1 atm})(0.156m^2)=24000N$
$F_t=F_i-F_o=24000N-(101325\frac{N}{m^2})(0.156m^2)=8200N$