Like all questions in this mission, the work done by non-conservative forces must be related to the changes in energy of the object (see Know the Law section). In the case of the skier on the practice hill, the potential energy equation (see Formula Frenzy section) can be used to determine the initial and final potential energy of the skier. Since the skier is at ground level in the final state, the height and potential energy can be regarded as zero. The initial kinetic energy is 0 J since the skier starts from rest. The final kinetic energy can be determined by using the relationship between work and energy. The change in total mechanical energy is caused by and equal to the work done upon the object. The work is stated in the question statement. This work value is equal to the difference between initial and final mechanical energy. In equation form
KEi + PEi + Wnc = KEf + PEf
The final kinetic energy can be calculated using the above equation.
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