Three identical smooth cylinders each of mass  $\sqrt{3}$ kg are placed as shown in the figure. Find normal reaction between cylinder A and cylinder B.  $\left(\mathrm{g}=10\mathrm{m}/{\mathrm{s}}^2\right)$

mg can be resolved into two forces of equal magnitude F inclined at an angle  
with each other
$\begin{array}{l}\therefore \sqrt{{\mathrm{F}}^2+{\mathrm{F}}^2+2{\mathrm{F}}^2\cos {60}^0}=\sqrt{3}\mathrm{g}\\ \Rightarrow \begin{array}{r}3{\mathrm{F}}^2=3{\mathrm{g}}^2\\ \mathrm{F}=\mathrm{g}\text{ or }\mathrm{F}=10\mathrm{N}\end{array}\end{array}$
Hence, reaction of B on A = 10 N