The correct option is B
(VO)1(VO)2=12
Orbital speed of a satellite is given by,
VO=√GMr
∴(VO)1=√GMr1
(VO)2=√GMr2
∴(VO)1(VO)2=√GMr1×√r2GM
(VO)1(VO)2=√r2r1 .....(1)
The period of revolution of a satellite is given by,
T2∝r3⇒(T1T2)2=(r1r2)3
T1T2=81⇒(r1r2)3=(81)2
⇒r1r2=41⇒r2r1=14 .......(2)
Using equation (1) and (2) we have,
(VO)1(VO)2=√14=12
Hence, option (B) is the correct answer.