As part of a training program, an athlete runs while holding 9.00 {rm kg} weights in each hand. As he runs, the weights swing through a 30.0 ^circ arc in frac{1}{3} {rm s}. His hands are 72 {rm cm} from his shoulder joint, and they are light enough that we can neglect their weight compared with that of the 9.00 {rm kg} weight he is carrying.
What force does the runner's hand exert on each weight at the bottom of the swing? answer should be in newtons