Question

In the polar moment of inertia the axis is perpendicular to _____________

(a) depends on the object

(b) x-axis

(c) z-axis

(d) y-axis

I got this question in an interview for internship.

The above asked question is from Moments of Inertia of Areas topic in section Centres of Gravity, Moments of Inertia, Orthographic Reading and Conversion of Views of Engineering Drawing

Answer 1

Right answer is (c) z-axis

For explanation: Polar moment of inertia is the sum of the moment of inertias of objects when axes are in same plane which are perpendicular to each other let us say x, y axis and polar moment of inertia is about z axis.