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”•Wnet = DKE

•Translational KE=1/2 mv2

Wnet = 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

Potential Energy

• Potential energy is stored energy.• Gravitational potential energy …Peg =mgy• See Example 6-7• Elastic Potential energy…The spring equation or Hooke’s law ...Pee =1/2 kx2

HOMEWORK…

• P174 17-21, 29-32