6.N- Law for rotation(定轴转动定律) I=la N-II Law for Rotation Net torque on a rigid body equals to the product of rotational inertia and angular acceleration it causes about same axis ∑△m 2 the moment of inertia or rotational inertia(转动惯量) on the axis The moment of inertia lis a measure of the rotational inertia of a body, which plays the same role for rotational motion that mass does for translational motion6. N-II Law for Rotation (定轴转动定律)  net = I N-II Law for Rotation —— Net torque on a rigid body equals to the product of rotational inertia and angular acceleration it causes about same axis. the moment of inertia or rotational inertia (转动惯量) on the axis. =  2 i i I m r The moment of inertia I is a measure of the rotational inertia of a body, which plays the same role for rotational motion that mass does for translational motion