To demonstrate that our setup and video-analysis technique can be used in the study of rotational dynamics with reliable results, we perform three experiments and use Tracker as our analysis tool. The first experiment focuses on the linear coefficient of rotational friction incurred in our system. The last two experiments are to validate the value of the moment of inertia ( I ) of the disc, as compared to the theoretical value, by using Newton's laws and the work–ener gy theorem. Here, the theoretical value is given by 1 / 2 Mr 2 , where M is the mass of the cylindrical plate, ie 187 . 5 g, and r is its radius, ie 6 . 96 cm