Solve the all parts of following problem:
Problem: In a retelling of the ancient tale of David and Goliath, David holds a 1.6 m rope at its midpoint, and twirls a 1 kg stone attached at the farther end. The stone is revolving at 3.1 m/s in a horizontal circular path 0.4 m above David's head.
Part A: What is the centripetal force?
Part B: What is the tension in the rope?
Please show your results in detailed calculations.