Question

Figure shows a cubical box that has been constructed from uniform metal plate of negligible thickness. The box is open at the top and has edge length 40 cm. The z coordinate of the centre of mass of the box in cm, is

Answer 1

Given: $l=40cm$
If $m$ is mass of one plate and there are five sides, out of then four verticle sides of square have center of mass at $z=20cm$, side at bottom will have center of mass at $z=0$
$z_{cm}=\frac{m\left(20\right)+m\left(20\right)+m\left(20\right)+m\left(20\right)+m\left(0\right)}{5m}$
$=16cm$
Final Answer:16