The velocity ratio of the differential wheel and axle is
A
$$\frac{{\text{R}}}{{{{\text{r}}_1} - {{\text{r}}_2}}}$$
B
$$\frac{{2{\text{R}}}}{{{{\text{r}}_1}}}$$
C
$$\frac{{3{\text{R}}}}{{{{\text{r}}_1} - {{\text{r}}_2}}}$$
D
$$\frac{{2{\text{R}}}}{{{{\text{r}}_1} + {{\text{r}}_2}}}$$
Correct Answer: $$\frac{{2{\text{R}}}}{{{{\text{r}}_1}}}$$
