Here is the problem. The free-fall velocity of a parachutist can be simulated as du/dt=g-Cd/m u^2 where u = velocity (m/s) t= time (s) g = acceleration due to gravity (9.81 m/s2). Cd = drag coefficient (kg/m), and m = mass (kg). For a 80-kg parachutist, solve this equation numerically from t = 0 to 30 s given that u(0) = 0. During free fall, Cd = 0.25 kg/m. However, at t = 10 s the chute opens, whereupon Cd = 5 kg/m. Please help! from were I should start solving this problem!