Tarzan tries to cross a river by swinging from one bank to the other on a vine that is 10.7 m long. His speed at the bottom of the swing, just as he clears the surface of the river, is 8.7 m/s. Tarzan does not know that the vine has a breaking strength of 1.3*10^3 N. The acceleration of gravity is 9.81 m/s^2. What is the largest mass Tarzan can have and make it safely across the river? Answer in units of kg.