Answer
${Y_{com}} = - 4.4\,cm$
Work Step by Step
We know that the formula for the y-coordinate of the center of mass is:
${Y_{c.o.m.}} = \frac{{{m_1}{y_1} + {m_2}{y_2}{m_3}{y_3}}}{{{m_1} + {m_2} + {m_3}}}$
We also know that ${m_1} = 14\,g$, ${m_2} = 42\,\,g$ and ${m_3} = 14\,\,g$. Also ${y_1} = - \frac{L}{2}$, ${y_2} = 0$ and ${y_3} = - \frac{L}{2}$.
Substituting these values in the formula, we get
${Y_{c.o.m.}} = - \frac{L}{2} = - \frac{{22}}{5} = - 4.4\,cm$
