A small disc of radius 2cm is cut from a disc of radius 6cm. If the distance their centers is 3.2cm, what is the shift in the center of mass of the disc?

Options

A. `0.4` cm
B. `2.4` cm
C. `1.8` cm
D. `1.2` cm

Answer

A

Explanation

Big disc
`A=pi(6)^(2)` ,
`x_(1)=0, y_(1)=0`
Small disc
`a=pi(2)^(2)`
`x_(2)=3.2, y_(2)=0`
`x_(COM)=(Ax_(1)-ax_(2))/(A-a)=(pi(6)^(2)xx0-pi(2)^(2)xx3.2)/(pi(6^(2)-2^(2)))`
= `-0.4` cm .