Two girls of weights 40 kg and 60 kg stand at A and B and are 10 m apart. They pull on a massless string stretched between them. Then they will meet at :

Options

A. 4 m from A
B. 6 m from A
C. Mid point of AB
D. None of these

Answer

B

Explanation

Since external force is zero therefore centre of mass will remain at rest and the two girls will meet at the centre of mass C. The distance of centre of mass from A is given by
`x=(m_(1)xx0+m_(2)xx10)/(m_(1)+m_(2))=(60xx10)/(100)=6m`

Thus two girls will meet at a distance 6 m from pt. A.