The time period of a satellite, revolving above earth's surface at a height equal to R will be (Given $g = \pi ^ { 2 } \mathrm {~m} \mathrm {~s} ^ { - 2 } , R =$ radius of earth)\\
(1) $\sqrt { 2 \mathrm { R } }$\\
(2) $\sqrt { 8 \mathrm { R } }$\\
(3) $\sqrt { 32 \mathrm { R } }$\\
(4) $\sqrt { 4 \mathrm { R } }$