An 85 kg object is moving at a constant speed of 15 m/s in a circular path, which has a radius of 20 meters. what centripetal force is exterted on the body?

As always,. F = M A. Centripetal acceleration = V-squared / R. So F=M V-squared/R. =. 85 x 225 / 20. = 956.25 Newton's (about 215 pounds). That's the force required to keep that mass moving at that speed around that circle. If the force is less, or not there, then the 85 kg moves slower, or leaves that path.