A square plate of mass 120 ext g and edge 5.0 ext cm has a uniform angular acceleration of 0.2 ext rad/s ^2 . Calculate the torque on the plate if it rotates about a diagonal with the same angular acceleration.

Step-by-step solution

For a square lamina, the moment of inertia about any axis in its plane through the center is I = 1 12 m a^2 . Here m = 0.12 kg and a = 0.05 m . Thus I = 1 12 (0.12)(0.05^2) = 2.5 10⁻⁵ kg m ^2 . The torque is = I = (2.5 10⁻⁵)(0.2) = 5.0 10⁻⁶ N m .