12. An 80.0 kg skydiver jumps out of a balloon at an altitude of1060 m and opens
ID: 1722380 • Letter: 1
Question
12. An 80.0 kg skydiver jumps out of a balloon at an altitude of1060 m and opens the parachute at analtitude of 170 m. (a) Assuming thatthe total retarding force on the diver is constant at 50.0 N withthe parachute closed and constant at 3600 N with the parachuteopen, what is the speed of the diver when he lands on theground?1 m/s
(b) Do you think the sky diver will be injured? Explain.
2
(c) At what height should the parachute be opened so that the finalspeed of the skydiver when he hits the ground is 5.00 m/s?
3 m
(d) How realistic is the assumption that the total retarding forceis constant? Explain your answer.
Explanation / Answer
if we apply the law of conservation energy thenwe get Wnc = (KE +PEg)f - (KE +PEg)i then we get (f1 cos180o)d1 + (f2 cos180o) d2 =[(1 / 2) m vf2 + 0] - [0 + m gyi] vf = [2 (g yi -(f1 d1 + f2 d2) /m)] = {2[(9.80 m /s2) (1000 m) - ((50.0 N)(800 m) + (3600 N) (200 m) /80.0 kg)]} = ......... m / s (b) this depends on the answer of (a) (c) if we apply the law of conservation energythen we get Wnc = (KE +PEg)f - (KE + PEg)itaking d1 = 1000 m - d2 vf = 5.00 m / s (f1cos180o) (1000 m - d2) + (f2cos180o) d2 = [(1 / 2) mvf2 + 0] - [0 + m g yi] on solving we get d2 = (m g) yi - (1000m) f1 - (1 / 2) m vf2 /f2 - f1 = ......... m (d) in reality the air drag will depend on theskydivers speed it will be larger than her weight only afterchute is opened it will be nearly equal to his weight before heopens the chute and again she touches down when ever shemoves near terminal speed vf = 5.00 m / s (f1cos180o) (1000 m - d2) + (f2cos180o) d2 = [(1 / 2) mvf2 + 0] - [0 + m g yi] on solving we get d2 = (m g) yi - (1000m) f1 - (1 / 2) m vf2 /f2 - f1 = ......... m (d) in reality the air drag will depend on theskydivers speed it will be larger than her weight only afterchute is opened it will be nearly equal to his weight before heopens the chute and again she touches down when ever shemoves near terminal speed
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