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From the circular disc of radius 4R two ...

From the circular disc of radius `4R` two small discs of radius R are cut off. The centre of mass of the new structure will be at

A

`hatiR/5+hatjR/5`

B

(b) `-hatiR/5+hatjR/5`

C

(c) `-hatiR/5-hatjR/5`

D

(d) None of the above

Text Solution

Verified by Experts

The correct Answer is:
D
`r_(CM)=(A_1r_1-A_2r_2-A_3r_3)/(A_1-A_2-A_3)`
`=(pi(4R^2)(0)-(piR^2)(3Rhati)-(piR^2)(3Rhatj))/(pi(4R)^2-piR^2-piR^2)`
`=(-(3R)/(14)hati-(3R)/(14)hatj)`
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Knowledge Check

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