You have seen dogs shake to shed water from their fur. the motion is complicated, but the fur on a dog's torso rotates back and forth along a roughly circular arc. water droplets are held to the fur by contact forces, and these forces provide the centripetal acceleration that keeps the droplets moving in a circle, still attached to the fur, if the dog shakes gently. but these contact forces - like static friction - have a maximum possible value. as the dog shakes more vigorously, the contact forces cannot provide sufficient centripetal acceleration and the droplets fly off. a big dog has a torso that is approximately circular, with a radius of 16 cm . at the midpoint of a shake, the dog's fur is moving at a remarkable 2.5 m/s . part a) what force is required to keep a 10 mg water droplet moving in this circular arc? part b) what is the ratio of this force to the weight of a droplet?