The diagram shows the vertical cross-section ABCD of a surface. BC is a circular arc, and AB and CD are tangents to BC at B and C respectively. A and D are at the same horizontal level, and B and C are at heights 2.7 m and 3.0 m respectively above the level of A and D. A particle P of mass 0.2 kg is given a velocity of 8 m s^-1 at A, in the direction of AB (see diagram). The parts of the surface containing AB and BC are smooth.

1. Find the decrease in the speed of P as P moves along the surface from B to C.
2. The part of the surface containing CD exerts a constant frictional force on P, as it moves from C to D, and P comes to rest as it reaches D.
3. Find the speed of P when it is at the mid-point of CD.