A paratrooper w/ a fully loaded pack has a mass of 120kg. The force due to air resistance on him when falling w/ an unopened parachute has magnitude

Question

F(sub)d = bv^2, where b=0.14 N*s/m^2.

a) if he is falling w/ an unopened parachute at 64m/s, whats is the force of air resistance acting on him?

b) what is his acceleration?


c) what is his terminal velocity?

I figured that to be:
v(sub)t= sqrt (120 *9.8) / (0.14)


Can someone please help me find acceleration and the force of air resistance?

Thank you!! :)

Answer 1

a) Use the formula that was provided. The drag force is
F = b*(64)^2 = 573 N at v = 64 m/s

b) a = F/Mass

c) Let the terminal velocity be V. It occurs when bV^2 = M g. That is before the parachute opens.

V = sqrt (M g/b)
which is what you had

The value of b will increase by a large factor when the parachute opens, but the question is not concerned with that.