Two particles of masses in th ration 1:2 are placed along a verttical line . The lighter particle is raised through a height of 9 cm. To raise the centre of mass of the system by 2 cm, the heavier particle should be

Options

A. moved 1.5 cm downward
B. moved 2 cm upward
C. moved 1.5 cm upward
D. moved 2 cm downward

Answer

A

Explanation

Let initially particles are at origin. Their masses ar m and 2m

`2(mxx9+2mxy_2)/(3m)`
`2= (9+2y_2)/(3)`
`y_2 =-1.5 cm`
So, second particle must be moved 1.5 cm downward.