Originally Posted by

**chengbin** Thanks for all your hard work.

@topsquark

This is not a problem from a textbook. I'm trying to model someone falling, but has reached terminal velocity already, hence when t = 0, v = 50. I wanna know his speed 2 seconds after he releases his parachute at t = 0.

The value for k is from the drag equation, $\displaystyle \frac {1}{2}\rho v^2C_dA$

p is 1.22 (density of air)

Cd = 2 (large drag for a parachute)

A = 100m^2 (area of the parachute)

The fact you experts are having trouble with this is making me doubt if I'm doing this question correctly.