The diagram shows a vertical cross-section of a surface. A and B are two points on the cross-section. A particle of mass 0.15 kg is released from rest at A.

1. Assuming that the particle reaches B with a speed of 8 m s^-1 and that there are no resistances to motion, find the height of A above B.
2. Assuming instead that the particle reaches B with a speed of 6 m s^-1 and that the height of A above B is 4 m, find the work done against the resistances to motion.