JIPMER2008PhysicsCenter of Mass, Momentum and Collision
A small disc of radius 2 cm is cut from a disc of radius 6 cm . If the distance between their centres is 3.2 cm , what is the shift in the centre of mass of the disc?
Options
- A0.4 cm
- B2.4 cm
- C1.8 cm
- D1.2 cm
Correct answer
A. 0.4 cm
Step-by-step solution
The situation can be shown as : Let radius of complete disc is a and that of small disc is b . Also let centre of mass now shifts to O ₂ at a distance x₂ from original centre. The position of new centre of mass is given by X_ CM = - b^2 x₁ a^2- b^2 Here, a=6 ~cm , b=2 ~cm , x₁=3.2 ~cm Hence, X_ CM = - (2)^2 3.2 (6)^2- (2)^2 aligned & = 12.8 32 & =-0.4 ~cm aligned