Terminal Velocity + Drag Force

  • #1

Homework Statement



A sky diver of mass 79.5 kg jumps from a slow-moving aircraft and reaches a terminal speed of 53.0 m/s.

(a) What is the acceleration of the sky diver when her speed is 30.0 m/s?

What is the drag force on the diver when her speed is the following?
(b) 53.0 m/s (answer in N)
(c) 30.0 m/s (answer in N)



Homework Equations





The Attempt at a Solution



I found parts a and b (correct on Webassign), but I can't get part c.):

a.) a= 6.792 m/s2
b.) 779.1 N

Would part c.) just be: mg-ma???

(779.1)-(79.5)(6.792)
= 239.096 (WebAssign says it's incorrect)
 

Answers and Replies

  • #2
rl.bhat
Homework Helper
4,433
7
Drag force in air ia approximately proportional to v^2. So f = D*v^2.
Using the result from b, find D.
Use this value to solve c.
 
  • #4
Redbelly98
Staff Emeritus
Science Advisor
Homework Helper
Insights Author
12,102
130
Your answer looks good. Does WebAssign concern itself with doing significant figures properly?
 

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