The curvature and torsion: how to distinguish the shape of a curve 
Example 3
Let \[\begin{array}{rl} f:[-1,1] & \rightarrow\mathbb{R}^{2}\\ t & \rightarrow\left(t^{3},\,t^{2}\right) \end{array}\]
Then \(f'(t)=\left(3t^{2},2t\right)\); \(v(t)=\left|f'(t)\right|=\sqrt{4t^{2}+9t^{4}}\) and the trace of this curve is:
Observe that \(f'(0)=(0,0)\), that is, the velocity is zero at \(t=0\).
