7.2. Changes in Energy

Question 1

εf − εi = (Work)engine − (Work)friction

Answer 1

• εf is the final kinetic energy of the object
• εi is the initial kinetic energy of the object
• (Work)engine is the energy caused by driving force acting
  on the object
• (Work)friction is the energy used up by frictional force or
  any resistive force