1, 2, 5 are figures that have patterns formed from four lines curved in a concave direction. 3, 7, 8 are figures that have patterns formed from four lines curved in a convex direction. 4, 6, 9 are figures that have patterns formed from these straight lines.
Centrifugal force is the fictitious force that pulls out from the center on the body we feel while moving in the circular path. It increases with the rate of rotation of the axis i.e, acceleration of the body.