The tremendous development of information and communication technology, especially the existence of smartphone, has a huge impact on people lifestyle. Smartphone technology allows several of applications to make life easier. Most of teenagers in Indonesia have been familiar with smartphone technology which can be potentially used on educational field. In this study, we have developed mobile learning apps to help high school students in learning simple harmonic motion. In the past time, students who want to study physics by themselves usually only could rely on traditional books. With this mobile learning app, high school students can study anywhere and anytime. The developed mobile learning apps have been tested to a group of students consists of 34 high school students. We used one-group pre-test-and-post-test design to investigate the use of mobile learning app impacts on the students' learning achievements. The average N-gain score of 0.33 shows that there is a medium gain of students' learning achievements.