The purpose of this study was to investigate the conceptual knowledge of the motion of two objects on an inclined and/or horizontal surface, in undergraduate physics students at the Central University of Technology, Free State (CUT), Bloemfontein campus. The study was conducted with 103 introductory to physics students in B.Ed. (FET) Natural Science programme in the faculty of Humanities as respondents. A pre-test was administered to test and investigate the students’ existing knowledge and was based on the concept of problem-solving. The results indicated that the majority (more than 80%) of students had major difficulties with where and how to start in order to solve the problems. They lacked basic knowledge of free-body diagram and vector analysis, as a result, they could not apply or deduce equations to solve. A follow-up remedial intervention was conducted to clear up the confusion and to assist them to acquire necessary and basic skills and knowledge of vector analysis, viz., free-body diagram, finding vertical and horizontal components of vectors, equilibrium conditions as well application of Newton’s Second law of motion. With this skill, they were introduced to deriving equations to calculate the acceleration of the objects and the tension of the wire connecting them (mathematical skills). A post-test was administered and the results indicated a great improvement (more than 70%) in the vector analysis and mathematical application of vectors in problem solving. Follow-up interviews indicated deficiencies and confusion from their previous learning, although some students (about 30% of the 70%) indicated that they need to be taught the concept first before the test. Their reasoning was they forgot the concept.