Question

Five uniform circular plates, each of diameter b and mass m, are laid out in a pattern shown. Using the origin shown, find the y coordinate of the centre of mass of the five-plate system.

• A. b/5
• B. b/3
• C. 4b/5
• D. 2b/5

Answer 1

The correct option is C 4b/5

We know that as per definition of centre of mass

Y${}_{cm}=\frac{\int ydm}{\int dm}=\frac{bm+2bm+bm}{5m}=\frac{4b}{5}$