This study developed an online observable augmented reality dynamics experimental system that can be used in the current COVID-19 pandemic, where face-to-face experiments are difficult to conduct. The developed system enables the broadcast of mass point and rigid body measurements using an online depth camera, and remote observation using mobile devices. The mass point measurement enables students to quantitatively analyze results by utilizing 2D projected trajectories. Students can view the virtual trajectories by modifying the gravity or restitution coefficient, which is not possible in real experiments. The complex motion of the rigid body can be shown separately as the motion of the center of gravity and the moment of inertia with respect to the center of gravity.