- #1

- 178

- 1

[tex]

\frac{\partial \vec{v_i}}{\partial \dot{q_j}} = \frac{\partial \vec{r_i}}{q_j}

[/tex]

I do not understand how he arrives at this equation. He states that this comes from equation 1.46, which is

[tex]

v_i = \frac{dr_i}{dt} = \frac{\partial r_i}{\partial q_k}\dot{q_k} + \frac{\partial r_i}{\partial t}

[/tex]

where the summation convention is implied, but I do not see how he goes from here to 1.51. Any help would be appreciated. Thanks.