Objects accelerate when the net force acting on them divides by their mass, according to Newton's second law of motion. The second law states that force and acceleration are directly related, while mass and acceleration are inversely related.
To solve this problem we start from the premise that energy is conserved. This means that the energy that the skier has at the beginning of the slope is equal to the energy he has at the end of the slope.
When the skier is at the top of the slope (point 1) his kinetic energy is minimal and his potential energy is maximum. Let's call to the energy in point 1.
mgh = potential energy
When the skier is at the lowest point of the slope (point 2) his kinetic energy is maximum and his potential energy is minimal. Let's call the energy in point 2.
= kinetic energy
= energy lost by friction
By the law of conservation of energy we know that: