Chapter 6-5 to 6-8 Review
6-5 Conservative and Nonconservative Forces
Net work is the sum of work done by conservative and nonconservative forces:
This is equal to the change in kinetic energy of the system:
We can rewrite work done by conservative forces as a negative change in potential
energy (as gravity does positive work on an object, it loses potential energy):
So the work done by nonconservative forces is the change in KE plus the change in PE:
6-6 Mechanical Energy and its Conservation
If there are only conservative forces acting, then the sum above equals zero:
Total Mechanical Energy- sum of the kinetic and potential energy of the system. Note
that the potential energy depends on the position we decide to call zero potential energy.
Conserved Quantity- a quantity that stays constant throughout a process. In our case, the
total mechanical energy of a system stays constant if only conservative forces are acting.
6-7 Problems using Conservation of Energy
6-8 Other Forms of Energy