[填空题]
(a) What is the acceleration of two falling sky divers fc 5u okcry6rzy7r1+/(mass 132 kg includiqm*qbo/v6 hro5ez1uw1 j* xu,ng parachute) whew*u o1e uq /o6* mzbvjh1,x5rqn the upward force of air resistance is equal to 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.
