This is an interactive homework problem designed to promote student understanding of when to use the Work-Energy Theorem to simplify problem solving.  The problem gives the mass, initial velocity, coefficient of friction, and stopping distance of an empty truck traveling on a straight road.  Students must determine the stopping distance if the truck were fully loaded, doubling its mass.   A user-activated "help" sequence is provided for finding solutions within the framework of both the Work/Kinetic Energy Theorem and Newton's Second Law.  To promote critical thinking, immediate feedback is received for both correct and incorrect responses.  This item is part of a larger collection of interactive homework problems for introductory physics.