# Work and Energy - Mission WE5 Detailed Help

 If both conservative (i.e., internal) and non-conservative (i.e., external) forces are doing net work upon an object, then the total mechanical energy of the object ____.
 Conservative forces, when they do work upon an object, have no effect upon the total amount of mechanical energy. See Dictionary section. On the other hand, when non-conservative forces do work upon an object, the total amount of mechanical energy is changed. See the second Dictionary section. Regardless of whether conservative forces are doing work or not, the fact that non-conservative forces do net work means that the total mechanical energy of the object will change. Whether the amount of mechanical energy increases or decreases depends on whether the net work done by non-conservative forces is positive work or negative work.
 Definition of Conservative Force: All the different types of forces that could do work upon an object can be categorized as either conservative or non-conservative forces. A conservative force is a type of force that serves to transform an object's energy between kinetic and potential. When only conservative forces do net work upon an object, the energy of the object changes forms (KE to PE or vice versa) without changing the total amount of mechanical energy.
 Definition of Non-conservative Force: All the different types of forces that could do work upon an object can be categorized as either conservative or non-conservative forces. A non-conservative force is a type of force that changes the total amount of mechanical energy possessed by an object. When non-conservative forces do work upon an object, the total amount of mechanical energy changes.