Question

Determine the drag coefficient of a 75 kg skydiver with a projected area of 0.33 m2 and a terminal velocity of 60 m/s.


By how much would the skydiver need to reduce his project area so as to double his terminal velocity? How would he accomplish this?

Answer 1

(a)-Terminal velocity for a falling object occurs when the drag on the object equals its weight. R = W½ρCAvt2 = mg Solve for projected area, substitute values, and compute. (The density of air is in this book somewhere.) C = 2mgρAv2C = 2(75 kg)(9.8 m/s2)(1.207 kg/m3)(0.33 m2)(55 m/s)2
=C=1.22

(b) -Solve for terminal velocity this time, instead of drag coefficient. vt = √2mgρCA 
=vt ∝ √1 ⇒ 2vt ∝ √1A¼A