Fundamental Limits of Shaking a Baby.

Abstract

Basic physics places limits on the mechanics involved in shaking a baby. Fundamental definitions and practical limitations are used to compare shaking with car crashes and low-level falls. First-order mathematical considerations applied to a 6-month-old infant determine an angular velocity limit for head rotation around 75 rad/s and maximum angular acceleration less than 1600 rad/s2 without impact. By comparison, results from a low-level fall of 0.76 m (30 inches) yield values of 83 rad/s and 13,000 rad/s2 in a practical worst-case scenario.