The results of the experiment based on Newton's laws are given in table 1 . We present angular acceleration and torque obtained for different masses. The recording speed of 30 fps corresponds to a duration of t = 0 . 033 s between two adjacent frames. The slopes of the plot between the angular displacement and the square of the time of travel in figure 5 yield the angular acceleration of the cylindrical plate for various masses. Tension and torque are obtained from equations ( 4 ) and ( 5 ), respectively . In addition, the maximum torque due to rotational friction ( τ max f ) in the movie (at t ∼ 0 . 5 s) can also be evaluated by using equation ( 2 ) for each mass, clearly indicating that it is only about 4 . 0–7 . 6% of that of string tension as shown in the parentheses in the last column of table 1 . Therefore, it is sensible to neglect the impact of rotational friction in this experiment. The moment of inertia of the disc can then be found from the linear regression using equation ( 3 ) as shown in figure 6 .T h e resulting moment of inertia is 4 . 52 × 10 − 4 ± 0 . 21 × 10 − 4 kg m 2 , about 0 . 4% deviation