Whenever there is an interchange between the potential energy and kinetic energy, the total mechanical energy remains constant. This is principle of conservation of mechanical energy.
i.e K + U = constant provided there are no frictional forces.
The condition for mechanical energy to be conserved is that there should be no frictional forces. This condition is only applicable in vacuum.
(a) Calculate the change in the gravitational potential energy of the skier between A and B. (b) If 75% of the energy in part (a) becomes the kinetic energy at B, calculate the speed at which the skier arrives at B.(Take g = 10 ms-2).