Ben’s favorite ride at the Barrel-O-Fun Amusement Park is the Flying Umbrella, which is lifted by a hydraulic jack. The operator activates the ride by applying a force of 72 N to a 3.0 cm diameter cylindrical piston, which holds the 20,000 N ride off the ground.

What is the diameter of the piston that holds the ride? (The area of a circular piston: A = πr²)