Question

Two point masses of mass `4m` and `m` respectively separated by `d` distance are revolving under mutual force of attraction. Ration of their kinetic energies will be:
A. `1:4`
B. `1:5`
C. `1:1`
D. `1:2`

Answer 1

Correct Answer - a
They will revolue about this centre of mass position of centre of mass
`0=4m(-x)+m(d-x)`
`x=d/5`
They will same ` omega`
`(K_(4m))/(K_(m))=(1/2I_(4m)omega^(2))/(1/2I_(m)omega^(2))`
`(K_(4m))/(K_(m))=(1/2(4m)(d//5)^(2))/(1/2(m)(4d//5)^(2))implies(K_(4m))/(K_(m))=1/4`