A roller coaster is designed such that riders experience " weightlessness" as they go round the top of a hill whose radius of curvature is 20m. The speed of the car at the top of the hill is between

Question

$\begin {array} {1 1} (1)\;13\: m/s\: and \: 14\: m/s & \quad (2)\;14\: m/s\: and \: 15\: m/s \\ (3)\;15\: m/s\: and \: 16\: m/s & \quad (4)\;16\: m/s\: and \: 17\: m/s \end {array}$