U the gravitational force is proportional to 1/ R3 , the square of time period of revolution is proportional to
R2
R3
R4
None
F=k/R3Now mv2R=kR3 or V=1RkmThe frequency of revolution v is given byv=V2πRSo, the time period of revolutionT=1v=2πRV=2πR2mkor T∝R2 or T2∝R4