Gibbons, small asian apes, move by brachiation, swinging below a handhold to move forward to the next handhold. a 8.7 kg gibbon has an arm length (hand to shoulder) of 0.60 m. we can model its motion as that of a point mass swinging at the end of a 0.60-m-long, massless rod. at the lowest point of its swing, the gibbon is moving at 3.7 m/s. what upward force must a branch provide to support the swinging gibbon?