Hammer throw
Rotation and ejection speed in the discipline of Hammer Throwing
Author:
Title 4
Learning objectives :
This activity allows students to understand the transformation of circular motion into linear motion. It develops the ability to analyze a sporting performance with scientific tools.
Concepts covered
Uniform circular movement; Conservation of angular momentum; Ballistic; Rotary/linear motion conversion; Optimal shooting angle
What students will do :
The student analyzes a hammer throw video using the FizziQ kinematic analysis module to determine the ejection speed. After having carried out the pointing image by image the student compares this experimental value with a theoretical value calculated from the rotation speed then thinks about the optimal ejection angle to maximize the distance.
What is required :
Smartphone or tablet with the FizziQ application; Hammer throw video available in Cinematic Video Library; FizziQ experience notebook
Scientific background :
The hammer throw perfectly illustrates the transformation of a circular movement into a linear movement. In this Olympic discipline inherited from Celtic traditions, the athlete rotates a mass (the "hammer", approximately 7.26 kg for men) attached to a cable, creating a circular movement before releasing it. The linear speed v at the moment of release is theoretically linked to the angular speed ω and to the radius r by the relation v = ω×r. Elite launchers can achieve ejection speeds of 27-29 m/s. Kinematic analysis makes it possible to experimentally verify this relationship and to identify possible deviations. These differences are mainly explained by the ejection angle: to maximize the range, the optimal angle is not horizontal but around 45° (in the absence of air resistance). In reality, taking into account aerodynamic resistance and release height, the optimal angle is slightly lower (40-43°). The trajectory after ejection follows a parabola modified by air resistance. In physical terms, this throw exploits several principles: centripetal force (cable tension) keeps the hammer in circular motion; inertia propels the hammer tangentially upon release; Conservation of angular momentum explains why the athlete accelerates their rotation during the final rounds. FizziQ's kinematic analysis tool allows you to precisely measure these parameters and understand the key factors for optimal performance.