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posted by  tea drinker on 11/3/2009 3:26:00 PM  |  status: Live  |  Earned Karma: 25

question help

Course Textbook Chapter Problem Needs by
Algebra Based Physics College Physics (8th) by Serway, Faughn, Vuille 5 49P 11/3/2009 at 6:00:00 PM
Question Details:
an 80kg skydiver jumps out of a balloon at an altitude of 1000m and opens the parachute at an altitude of 200m.  at what height should the parachute be opened so that the final speed of the skydiver when he hits the ground is 5.00 m/s?
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posted by john_r on 11/3/2009 3:45:16 PM  |  status: Live
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Response Details:


   if we apply the law of conservation energy then we get
   Wnc = (KE + PEg)f - (KE + PEg)i taking
   d1 = 1000 m - d2
   vf = 5.00 m / s
   here the retarding force on the diver is f1 with parachute closed and f2 with parachute open they must be assumed
   (f1 cos180o) (1000 m - d2) + (f2 cos180o) d2 = [(1 / 2) m vf2 + 0] - [0 + m g yi]
   on solving we get
   d2 = (m g) (1000 m) - (1000 m) f1 - (1 / 2) m vf2 / f2 - f1
        = ......... m
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