The equivalent of the Newton's second law for rotational motions is:
[tex]\tau = I \alpha[/tex]
where
[tex]\tau[/tex] is the net torque acting on the object
[tex]I[/tex] is its moment of inertia
[tex]\alpha[/tex] is the angular acceleration of the object.
Re-arranging the formula, we get
[tex]I= \frac{\tau}{\alpha} [/tex]
and since we know the net torque acting on the (vase+potter's wheel) system, [tex]\tau=16.0 Nm[/tex], and its angular acceleration, [tex]\alpha = 5.69 rad/s^2[/tex], we can calculate the moment of inertia of the system:
[tex]I= \frac{\tau}{\alpha}= \frac{16.0 Nm}{5.69 rad/s^2} =2.81 kg m^2 [/tex]