We know that the acceleration due to gravity g is: g = 9.81 m/s^2
So the centripetal acceleration (w) is:
w^2 = 1.5 g / r
w^2 = 1.5 * (9.81 m/s^2) / 5 m
w = 1.716 rad / s
To convert to rad to rev:
w = (1.716 rad / s) * (1 rev / 2π rad) * (60 s/min)
w = 16.4 rev/min