Calculating work done by helicopter/gravity, kinetic energy and speed?

AI Thread Summary
A helicopter lifts a 90 kg astronaut 13 m vertically with an acceleration of g/12. The force exerted by the helicopter is calculated as F=ma, resulting in 73.5 N, leading to a work done of 955.5 J. The gravitational force calculation using Wg=-mgd appears to be misunderstood, as the astronaut is not in free fall. The discussion highlights confusion regarding the interpretation of g/12 and the forces acting on the astronaut. Clarification on these calculations and concepts is sought for accurate results.
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A helicopter lifts a 90 kg astronaut 13 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/12. How much work is done on the astronaut by (a) the force from the helicopter and (b) the gravitational force on her? Just before she reaches the helicopter, what are her (c) kinetic energy and (d) speed?


F=ma
W=Fd
KE=1/2mv2


F=ma
F=(90)(9.8/12)=73.5
W=(73.5)(13)=955.5

Was not the right answer for a...for b I tried using Wg=-mgd but that didn't seem to work either. Am I misinterpreting what g/12 means? a and b were as far as I got. :( Any help would be appreciated, thank you!
 
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rockchalk1312 said:
A helicopter lifts a 90 kg astronaut 13 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/12. How much work is done on the astronaut by (a) the force from the helicopter and (b) the gravitational force on her? Just before she reaches the helicopter, what are her (c) kinetic energy and (d) speed?


F=ma
There are two forces acting on her. Consider - if the astronaut were just dangling there without moving, is the force exerted by the rope = ma = 0?
 
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