In your physics lab you are given a 12.1-kg uniform rectangular plate with edge
ID: 2197648 • Letter: I
Question
In your physics lab you are given a 12.1-kg uniform rectangular plate with edge lengths 66.9 cm by 47.3 cm. Your lab instructor requires you to rotate it about an axis perpendicular to its plane and passing through one of its corners and then prepare a report on the project. For your report you will need the plate's moment of inertia with respect to this axis. Calculate it here first. I got .677 by doing 1/12*M*(a^2+b^2) the hint is that this is the moment of inertia with respect to the axis through the center of mass and is incorrect.Explanation / Answer
you got moment of inertia about centre of mass as 0.677. Now you need to find moment of inertia about corner. let the distance of corner from center point be r. then moment of inertia about corner will be 0.677 + mr^2. Here r = half the diagonal length of give rectangle. or simply, (2r)^2 = a^2 + b^2.