.250 kg toy airplane is suspended from the ceiling in a conical pendulum. It flies with a radius of 10 cm, and has a period of 20 seconds. Find the centripetal force acting on the plane?

M V^2/R is the centripetal force for an object of mass M undergoing conical pendulum motion.

V = 2 pi R/20
= 0.0314 m/s

R = 0.1 meter