Two cylinders, referred to as Element $1$ and Element $2,$ are connected ot the center, with their ends fixed in place. torsional moment of $T=60$kips$-$in is applied at the connection etween the two cylinders.

letermine the rotational angle at this center connection point.

$I_{p1}=20i{n}^4,G_1=1000$kip$\frac{s}{i}{n}^2$

$I_{p2}=10i{n}^4,G_2=1000$kip$\frac{s}{i}{n}^2$