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

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SUMMARY

The discussion focuses on calculating the work done on a 90 kg astronaut lifted 13 m by a helicopter with an acceleration of g/12. The force exerted by the helicopter is calculated using F=ma, resulting in 73.5 N, leading to a work done of 955.5 J. The gravitational force is also considered, but the initial attempts to calculate it using Wg=-mgd were incorrect. The conversation highlights the need for clarity in interpreting the acceleration value of g/12 in the context of work and energy calculations.

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rockchalk1312
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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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