A cylindrical stone column of diameter 2R = 1.47 m and height H = 4.46 m is transported in standing position by a dolly. When the dolly accelerates or decelerates slowly enough, the column stands upright, but when the dolly’s acceleration magnitude exceed a critical value ac, the column topples over. (For a +ac the column topples

Question

A cylindrical stone column of diameter 2R = 1.47 m and height H = 4.46 m is transported in standing position by a dolly. When the dolly accelerates or decelerates slowly enough, the column stands upright, but when the dolly’s acceleration magnitude exceed a critical value ac, the column topples over. (For a > +ac the column topples
backward; for a < −ac the column topples
forward.)

help please
Calculate the magnitude of the critical acceleration ac of the dolly. The acceleration of gravity is 9.8 m/s2.
Answer in units of m/s2.