The purpose of this study was to give students a complete understanding of the derivative concept and at the same time help them to realize the critical applications of derivatives in many problems of physics, from which students see the close connection of mathematics and physics. Because this was a case study, the sample included only 30 grade 11 students in Ho Chi Minh City in Vietnam. The instrument included physics problems designed to show students the derivative development associated with some situations in physics. Reliable data were obtained, including students' worksheets, teacher conversations, and they were analyzed qualitatively to clarify students' understanding of derivative concepts and problem-solving abilities. It was reported that once the two-increase ratio boundary defined the derivative, the students involved in experiments realized the general significance of the derivative in calculating the instantaneous quantity change rate. This interdisciplinary approach also promoted the use of derivatives in many different contexts of science and practice, particularly in mathematics and physics.