Moment of inertia is diagonal and torques around the axes act independently of each other. When a body is free to rotate around an axis, torque must be applied to change its angular momentum. The amount of torque needed to cause any given angular acceleration (the rate of change in angular velocity) is proportional to the moment of inertia of the body. Moment of inertia may be expressed in units of kilogram meter squared (kg·m) in SI units and pound-foot-second squared (lbf·ft·s) in imperial or US units. Moment of inertia plays the role in rotational kinetics that mass (inertia) plays in linear kinetics
Linear regression linear relationship between the dependent variable and regressors. Thus the model takes the form where denotes the transpose, so that xβ is the inner product between vectors x and β. Often these "n" equations are stacked together and written in matrix notation as where Some remarks on notation and terminology: Example. Consider a situation where a small ball is being tossed up in the air and then we measure its heights of ascent "h" at various moments in time "t". Physics tells us that, ignoring the drag, the relationship can be modeled as where "β" determines the initial velocity of