PROBLEM SOLVING TACTICS
Tactic 2: Conservation of Mechanical Energy
Asking the following questions will help you to solve problems involving the conservation of mechanical energy. For what system is mechanical energy conserved? You should be able to separate your system from its environment. Imagine drawing a closed surface such that whatever is inside is your system and whatever is outside is the environment of that system.
Is friction or drag present? If friction or drag is present mechanical energy is not conserved.