Question

A rigid body consists of a $3kg$ mass connected to a $2kg$ by a massless rod. The $3kg$ mass is located at $r_1=2i+5jm$, and the $2kg$ mass at $r_2=4i+2jm$. Find the length of the rod and the coordinates of the centre of mass.

Answer 1

Length of rod=$\sqrt{{(2-4)}^2+{(5-2)}^2}=\sqrt{4+9}=\sqrt{13}$

Center of mass co-ordinate in $M(x,y)$

$x=\frac{3\times 2+4\times 2}{3+2}=\frac{14}{5}$

$y=\frac{3\times 5+2\times 2}{5}=\frac{19}{5}$