A uniform wheel of known rotational inertia \(I\) is mounted on a frictionless horizontal axle and is initially at rest at angular position \(\theta = 0\). A motor exerts a variable net torque on the wheel given by \(\tau(\theta) = C\theta^2\), where \(C\) is a positive constant and \(\theta\) is the angular displacement in radians. An experimenter measures the angular speed \(\omega\) of the wheel at various values of \(\theta\). To determine the value of \(C\) from the slope \(S\) of a linear graph, which quantities should be plotted on the vertical and horizontal axes, and what is the relationship between \(C\) and \(S\)?