Figure $3.$E$30$ shows several identical smooth rollers of weight $W$ each stacked on an inclined plane. Determine $($a$)$ the maximum number of rollers which will lie in a single row as shown and $($b$)$ all forces acting on roller A under condition $($a$).$

$[$Ans$.($a$)6$ Nos

$($b$)3\mathrm{.}11W({}_{}^{})=45,$

Fig. $3.$E$30$

$0\mathrm{.}062W(\frac{?}{\text{b}\text{a}\text{r}}())=60$

$2\mathrm{.}5W(\frac{?}{\text{b}\text{a}\text{r}}())=30$ and $W(darr).$