A particle of mass 1.2 kg moves in a straight line AB. It is projected with speed 7.5 m s^-1 from A towards B and experiences a resistance force. The work done against this resistance force in moving from A to B is 25 J.

1. Given that AB is horizontal, find the speed of the particle at B.
2. It is given instead that AB is inclined at 30° below the horizontal and that the speed of the particle at B is 9 m s^-1. The work done against the resistance force remains the same. Find the distance AB.