$1$

$1$ point

Session $10-$ Q$3$

The system below has appropriately balanced masses to be in equilibrium. If shaft $AB($not including the large gear$)$ has a diameter of $1\mathrm{.}0cm,m_2=9kg,g=9\mathrm{.}8\frac{m}{s^2},a_2=4cm,l_2=11cm,$ the elastic modulus of the material in the shaft is $206$ GPa with a Poisson's ratio of $0\mathrm{.}34,$ what is the angle of twist of shaft $AB$ in degrees? You might refer to $2015$ Exam $1.$