question_answer

A circular disc of radius R is removed from a bigger circular disc of radius 2R, such that the circumference of the discs coincide. The centre of mass of the new disc is\[(3,\infty )\]from the centre of the bigger disc. The value of a is [AIEEE 2007]

A)   \[(-\infty ,-3)\]              

B)        \[x=(2\times {{10}^{-2}})\cos \pi t\]      

C)   \[a=2\times {{10}^{-2}}m=2cm\]                  

D)        \[t=0,\]

Correct Answer: A

Solution :

[a] In this question distance of centre of mass of new disc from the centre of mass of remaining disc is.

Mass of remaining disc

NOTE The given distance must befor real approach to the solution.