Using Newton’s Laws to Determine the Quality of Bharatanatyam Dance Movements

Abstract

Bharatanatyam, an ancient Indian Classical dance form, places a heavy emphasis on dancers’ body positioning and usage of space, categorizing movements as ‘Good’ or ‘Bad’ qualitatively. The present experiment investigated the extent to which statics/kinematics can be used to evaluate the quality of a Bharatanatyam dance movement. The declared hypothesis was that the dancer’s body could be approximated as a rigid body/simple object, for analysis. Two Bharatanatyam movements, a one-dimensional jump, and a two-dimensional parabolic leap were each performed in a ‘Good’ and ‘Bad’ manner, recorded with calibration sticks in the background, and analyzed using Tracker. Inconsistencies within acceleration due to gravity values disproved the hypothesis. However, kinematics/statics comparisons between ‘Good’ and ‘Bad’ versions of both movements resulted in the following quantitative takeaways. In the one-dimensional movement, the ‘Good’ movement had a longer duration of free fall, a higher maximum vertical height, and a smaller horizontal displacement than the ‘Bad’ movement. The force exerted by the floor on the dancer was around 100 times the dancer’s body mass in the ‘Good’ movement vs. only 72 times in the ‘Bad’ movement. In the two-dimensional ‘Good’ movement, the dancer vertically jumped 2.15% of their body height and horizontally jumped 16% of their body height. In the ‘Bad’ movement, the same values were 0.895% and 21%. Calculating torque during launch revealed that the launch leg in the ‘Good’ movement was closer to than in the ‘Bad’ movement. The ratio of horizontal to vertical displacement was also 3 times lower for the ‘Good’ movement.