What force does the runner's hand exert on each weight at the bottom of the swing?

As part of a training program, an athlete runs while holding 9.00 kg weights in each hand. As he runs, the weights swing through a 30.0 degree arc in 1/3 sec. His hands are 72 cm from his shoulder joint, and they are light enough that we can neglect their weight compared with that of the 9.00 kg weight he is carrying.|||From a free body diagram We have F - m*g = m*r*蠅^2 (centripetal acceleration)





where 蠅 = 30*蟺/180/(1/3) = 1.57 rad/s


So F = m*(g + r*蠅^2) = 9.00*(9.80 + 0.72*(1.57)^2) = 104N