if you want you can consider it as a cube but then the the point on which the external force is acting is at the bottom right corner but it's z coordinate is equal to the z coordinate of the centre of the cube such that the torque produced in the z axis is zero
I am basing this off on the fact that axis of rotation passes through the point which has a net total of zero torque so in order to find the point i will choose a random point and solve so that the torque produced by gravity and the external force is zero.
things that are give or know...
1.to calculate torque we need a point right with respect to which we can calculate torque so what i am trying to achieve is find a point where the torque produced by gravity and external force is zero so that i can consider it as a point through which axis of rotation passes.
2.centre of mass...