2. Kinetic Energy and the Work/Energy Principle Energy is the ability to do work. Total energy is always conserved. A moving object can do work on another object it strikes. Kinetic energy is the energy of motion…from Greek kinetikos “motion” W net = DKE Translational KE=1/2 mv 2

3. W net = DKE This is the work/energy principle. The net work done on an object is equal to the change in its kinetic energy. See Examples 6-4, 6-5, 6-6

4. Potential Energy Potential energy is stored energy. Gravitational potential energy …Pe g =mgy See Example 6-7 Elastic Potential energy… The spring equation or Hooke’s law...Pe e =1/2 kx 2

5. HOMEWORK… P174 17-21, 29-32