[填空题]
(a) What is the accel /xhhm/.mz df.eration of two 6jl 0rez bs z0bz7j09p* ukl,afalling sky divers (mass 132 kg including parachute) when the upward force of air resistance is equal to0ra e0 zz,u7l zk*l6 s0bj9jpb one-fourth of their weight?
(b) After popping open the parachute, the divers descend leisurely to the ground at constant speed. What now is the force of air resistance on the sky divers and their parachute? See Fig. 4–39.
