The frictional torque transmitted in a flat collar bearing, considering uniform wear, is (where r₁ and r₂ = External and internal radii of collar respectively)

A. $$\frac{1}{2}\mu {\text{W}}\left( {{{\text{r}}_1} + {{\text{r}}_2}} \right)$$

B. $$\frac{2}{3}\mu {\text{W}}\left( {{{\text{r}}_1} + {{\text{r}}_2}} \right)$$

C. $$\frac{1}{2}\mu {\text{W}}\left( {\frac{{{\text{r}}_1^3 - {\text{r}}_2^3}}{{{\text{r}}_1^2 - {\text{r}}_2^2}}} \right)$$

D. $$\frac{2}{3}\mu {\text{W}}\left( {\frac{{{\text{r}}_1^3 - {\text{r}}_2^3}}{{{\text{r}}_1^2 - {\text{r}}_2^2}}} \right)$$

Answer: Option A