Two spheres A and B of masses 500 g and 10 kg are connected by a light rod of length 21 m. What is the position of the centres of mass? [Treat the spheres as particles]

Options

A. At 10 m from A
B. At 15 m from A
C. At 20 m from A
D. At 5 m from A

Answer

C

Explanation

C - Centre of mass
In such cases, we consider the mass moments, similat to the moment of a force.
`therefore 0.5 x = 10(21-x)`
`therefore (x)/(21-x)=(10)/(0.5)=(20)/(1)`
`therefore x = 420 - 20 x " " therefore 21 x = 420`
`therefore x = 20 m`
`therefore` The C.M. is at distance of 20 m from A.