MathDB
Putnam 1952 B4

Source: Putnam 1952

July 7, 2022
Putnamratiohemispherescylinder

Problem Statement

A homogeneous solid body is made by joining a base of a circular cylinder of height hh and radius r,r, and the base of a hemisphere of radius r.r. This body is placed with the hemispherical end on a horizontal table, with the axis of the cylinder in a vertical position, and then slightly oscillated. It is intuitively evident that if rr is large as compared to hh, the equilibrium will be stable; but if rr is small compared to hh, the equilibrium will be unstable. What is the critical value of the ratio r\slash h which enables the body to rest in neutral equilibrium in any position?