Resumen de Rotational-to-Translational Kinetic Energy Transfer for a Rolling Spool
Leonid Minkin, Anthony C. Zable
Kinetic friction exerted on a sliding object is a dissipative force responsible for the conversion of mechanical energy into heat. The direction of the kinetic friction force exerted on a sliding object always opposes the direction of its velocity at the point of contact with the surface (vpoc) but not necessarily its center-of-mass velocity (v). For various reasons, first-year physics students are rarely exposed to examples and lab experiences that emphasize kinetic friction beyond sliding objects without rotation and rolling objects without slippage. Unfortunately, this can result in the student misconception that mechanical energy loss due to kinetic friction is synonymous with translational kinetic energy loss. However, there are real-world examples where kinetic friction may increase the translational kinetic energy of a system, such as when rolling with slippage occurs between a vehicle’s tires and pavement. For example, rapidly pressing down on the gas pedal of an automobile can cause the tires to momentarily lose traction with the road surface when the magnitude of their tangential velocity at the point of contact with the pavement exceeds the magnitude of the forward velocity of the vehicle (i.e., the tires “peel out”). Conceptual exploration of phenomena, such as tire peel, can be an engaging and effective activity with which to challenge and correct students’ misconceptions with respect to kinetic friction interactions between sliding bodies.
