The ballistic pendulum experiment reimagined for rotational motion

Abstract Ballistic pendulum is a standard lab in introductory physics. It is primarily used to measure the velocity of a projectile by applying the fundamental physics laws of momentum conservation and energy conservation. Here the lab is reimagined as a vehicle to study dynamics of rigid bodies, a topic that is often perceived as complex and difficult by students. Using existing equipment and through a series of guided activities, students get to experiment with a rich set of rotational concepts, such as center of mass, moment of inertia, rotational kinetic energy, torque, physical pendulum, angular momentum and its conservation. It is demonstrated that the widely used linear model is an approximation of the rotational model detailed here. The difference is quantified in terms of velocity determination, energy loss, and forces in the system.