A laboratory demonstration involves collisions between small spheres and a rigid rod…
PHYSICS · Multi-part · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion
Problem
A laboratory demonstration involves collisions between small spheres and a rigid rod that can rotate in a horizontal plane about a fixed, frictionless pivot at point O. During the very short collision interval, substantial forces act at the pivot.
(a) Explain clearly why the linear momentum of the combined sphere–rod system is not conserved during the collision.
(b) Identify a physical quantity that is conserved during the collision and specify the axis about which this conservation applies. Provide a brief justification.
(c) Describe how making an appropriate choice of axis simplifies the analysis of the rod’s motion immediately after the collision.
(d) Suppose the pivot is no longer frictionless, so that a small constant torque acts on the rod during the collision. Explain qualitatively how this affects the conservation statement you gave in part (b) and what additional information would be needed to analyze the collision.