A person pulls a 50. kg box pictured below with a force of 100. N.  The coefficient of kinetic friction is 0.15.  How much of the force acts in the direction of motion?How much energy is transferred (via working) by the person who pulls the box a distance of 10. m?
Is the box moving at constant speed? Explain how you know. What does this tell you about the kinetic energy Ek of the system?
How much energy is stored as internal energy due to friction in the pulling process over the 10.m?
What eventually happens to this energy?