Answer:
r = 6.32 meters
Step-by-step explanation:
Given that,
The centripetal acceleration acting on the roller coaster,

Time taken by the car, t = 3.1 s
The centripetal acceleration act on an object when it moves in circular path. Its formula is given by :

v is the velocity of car,


On rearranging above equation,



r = 6.32 meters
So, the radius of the roller coaster loop is 6.3 meters. Hence, this is the required solution.